Harry Kane has transformed physically from a "chubby" teenager to a place "where he feels like a machine", says former team-mate Jermaine Jenas

When Tottenham Hotspur made their first trip to Real Madrid in the Champions League, a teenage Harry Kane was offering few signs of his future potential.

On 5 April 2011, while Spurs were being torn apart at the Bernabeu, the 18-year-old was sat on the Leyton Orient bench, patiently waiting for his chance to come on in a League One game against Plymouth.

When Tottenham made their next trip in the same competition, the maturing Kane was being linked with a £200m-plus move external-link to the 12-time European champions.

On 17 October 2017, the 24-year-old arrived in the Spanish capital as Tottenham and England's talisman - splashed across the front of Madrid's sports papers, the opponent to fear.

"His rise has been one of the biggest shocks of my footballing career," Jermaine Jenas, his former Spurs team-mate, said.

As Real Madrid prepare to face Spurs at Wembley on Wednesday, BBC Sport analyses whether Kane has the talent, mental strength and marketability to become a Galactico.

quote An English player on the front cover of Marca was very unusual Marca journalist Juan Castro

Is he 'a Real Madrid player'?

During his first spell as Real president between 2000 and 2006, Florentino Perez's pursuit of the world's most talented players and his extravagant spending to sign them coined a new term: Galacticos.

Portugal attacker Luis Figo and France midfielder Zinedine Zidane were the first of this new breed to arrive at the Bernabeu for world record fees, with Brazil striker Ronaldo, England captain David Beckham and striker Michael Owen also making the move over the next few seasons.

Perez left in 2006 amid criticism the club had become too focused on building its brand to the detriment of winning trophies, but returned in 2009 to complete the signing of Cristiano Ronaldo and then add Wales forward Gareth Bale four years later.

Kane, 24, is the same age as Ronaldo, Owen and Bale at the time of their respective transfers from the Premier League to Real Madrid, but does not have the same level of experience - at club, European or international level - as either of this trio.

Neither has he become a global star after illuminating a World Cup, European Championship or Champions League tournament.

Both Owen and Ronaldo had already won a Ballon d'Or - the prize awarded to the world's best player of the year - and had won several domestic honours with their respective clubs.

"In Spain, we don't consider him in the top 10 world-class players because he has only been playing a couple of years and is only playing at Tottenham, who are not in the Champions League semi-finals or final," Juan Castro, a football journalist at Madrid-based sports newspaper Marca, said.

"Maybe in the Premier League he is an enormous player but if you go into a Spanish bar then not everyone knows him. He is not a big star.

"He has to prove it in a Champions League or a World Cup, like Luis Suarez, to demonstrate he is a master."

However, Kane's goalscoring record in the Premier League compares favourably to Ronaldo, Owen and Bale - although only Owen was already considered a striker when he moved, with Ronaldo and Bale used more out wide.

While Kane has not scored as many goals as Owen did, he has netted at a quicker rate than the former Liverpool striker.

The leap to the Bernabeu

Playing for a big club is one thing. Playing for Real Madrid is another.

The ability to maintain composure in the opposition penalty area is what separates the greatest strikers from the rest. Even more so when 80,000 Madridistas are losing their cool around you.

Real Madrid legend Emilio Butragueno, who scored 171 goals in a 12-year spell at the Bernabeu, became known as El Buitre (The Vulture) because of his clinical finishing.

What was the key to the former Spain striker's success? "I left my mind blank for my body to act," he once said.

Kane's finishing ability has led to him being described as a "killer" striker by Spurs boss Mauricio Pochettino and former Real president Ramon Calderon believes the England international has the composure to succeed at the Bernabeu.

"You need to be calm in the penalty area otherwise you will be in trouble. You need to be cold to be a Real Madrid striker and I think he is. That's one of his main qualities," he said.

"But it is true that playing in the Bernabeu is difficult - sometimes even for players who have played for big clubs in different countries.

"It is different for some players when the fans boo - that doesn't happen at Manchester United or Liverpool or other teams.

"But maybe that is why we have built a legend and won so many trophies because of the demands from our fans - players know they have to perform."

Is he worth more than £200m?

Brazil forward Neymar became the first footballer to command a £200m transfer fee when he joined Paris St-Germain from Barcelona last summer and current Real president Perez believes Spurs would demand around £223m (€250m) for their prize asset.

"Kane is certainly worth around £200m because you would benchmark him against other strikers of his calibre," said Kieran Maguire, a sport finance expert at the University of Liverpool.

"It's a bit like when you are trying to work out how much a house is worth. You look at other houses down the street and if they are similar and going for 'X' then yours goes for 'X'.

"Kane is at a prime age, there is still room for improvement and Real could sign him on a five or six-year contract, spreading the cost over that period.

"For a club of their financial strength it would not be a issue."

Ronaldo is the world's highest-paid athlete, according to Forbes

Perez, having completed record deals for Figo, Zidane, Ronaldo and Bale over his two spells as president, has never been scared to splash the cash.

But for the 70-year-old construction magnate, a shrewd businessman with a net worth of $2.1bn, a big-money signing's playing ability has to be equalled by one thing: their commercial value.

Ronaldo, 32, is the world's highest-paid athlete, according to Forbes, raking in $35m of his $93m earnings last year through endorsements.

Real Madrid, with the Portugal forward as their poster boy, also brought in $216m through sponsorship deals - a revenue only bettered by Barcelona.

"Ronaldo is in a commercial league of his own and there will be a vacuum at Real Madrid when he hangs up his boots, whenever that might be," Maguire said.

"Kane is quite dull - in a good way, he just gets on with his games, scores goals and has a squeaky clean image - and is not glamorous in the same way as Cristiano is. Very few players are.

"But if Kane scores lots of goals then that will attract sponsors.

"In the main they are trying to attract the 15-34 male group who don't tend to watch a lot of television but do have disposable income.

"They are not bothered by the looks of the footballer, they want to be associated with a good footballer and a good guy - Kane falls into that bracket."

Is Kane better than Benzema and would he improve Real?

Since his breakthrough season in 2013-14, Kane has scored 86 Premier League goals. That tally puts him 11th on the list of leading scorers in Europe's top five leagues, with only Manchester City's Sergio Aguero bettering his record in the English top-flight.

However, Kane's strike-rate - calculated by his minutes per goal ratio - moves him up to eighth on the list.

Karim Benzema is the man seemingly most vulnerable should Kane move to the Bernabeu in the near future. And the 29-year-old Frenchman, despite being seventh on Madrid's all-time scoring chart, is not a striker fancied by everybody.

Since arriving from Lyon as a 21-year-old in June 2009, he has scored 182 goals in 375 games - just under one every two games - but former England captain and Barcelona striker Gary Lineker said Benzema was "overrated" and his record "nothing special".

"Real Madrid trust Benzema and believe in him," Marca journalist Castro said. "That's why they have given him a new three-year contract.

"At the moment it is a difficult situation for Real to sign another striker but if Kane has a good Champions League and World Cup - proving he can do it at the highest level - then it might change."

Kane has scored more goals than Benzema since making his breakthrough, but would the Englishman improve Real's fortunes if he replaced the Frenchman?

Yes, according to data experts Carteret Capital, external-link who work with Premier League and European clubs and use algorithms to determine the contribution players make to their team winning matches.

One aspect of their work is to analyse transfer targets, giving clubs an assessment of the impact a new signing would make.

We asked them to create a report looking at what influence Kane would have if he replaced Benzema at Real Madrid. Based on data since the start of the 2016-17 season, they found:

Kane has a significantly bigger impact on Tottenham's results than Benzema does on Real's results

If Kane had played instead of Benzema at Real Madrid this season, and had the same impact he has had at Spurs, then Kane would have improved their overall La Liga performance by 6.34%

That would increase Real's points haul in their opening 10 games from 20 points - which leaves them eight points behind leaders Barcelona - to 26 points.

'Madrid's denials over Kane interest mean nothing'

At this stage, Real Madrid are remaining coy about their interest in Kane - president Perez claiming signing the Londoner has "never entered his head".

However, the telltale signs of a Perez-led pursuit of a player are there to see: speculation about a future move in the Madrid-based newspapers, a public denial from a president keen not to upset a rival chairman from whom he has already snared two stars and flattering praise of the rumoured target from their coach - Zidane lauding Kane as a "complete" player.

"When you are in the middle of the season and already have important players for the team like Benzema, you cannot say you are interested in another player at another team because it can create a problem with your player and your team," said Calderon, who resigned as Real president in January 2009.

"It also puts more pressure on the player you are trying to sign and the price could be increased if you publicly admit your interest.

"Saying you are interested is not the wisest thing to do during a season. But saying you are not interested does not mean anything."

Harry Kane appeared on the front cover of Marca, Madrid's famous sports newspaper, before the Champions League game between Real and Spurs last month

With complex big-money moves taking months, years even, to push over the line, Calderon suggests informal talks between the two clubs might already be taking place.

Calderon was at the heart of one of Madrid's longest-running - and ultimately most successful - transfer pursuits when they targeted Ronaldo from Manchester United.

The 66-year-old says he was talking to Red Devils counterpart David Gill about the transfer for two years before the Portugal forward completed a world record £80m move in July 2009.

"I was talking to David for a long time and we knew the player wanted to come to Madrid," he said.

"When he said 'no, we are not selling now' I said 'OK'. Finally, in the case of Cristiano, we got the agreement, he got the agreement with Manchester United and it was done in the right way.

"But there are always friendly conversations between people running clubs - about if a player wants to come, if the club is willing to let them go, the price - that is normal conversation."

Is Kane open to a Real move?

While Real Madrid appear to flirt with the idea of signing Kane, the player has responded with some gentle encouragement to his potential suitor - at the same time as being non-committal about leaving Spurs.

Last month, Kane said he would "never rule out" playing abroad, but then added in another interview he would "love" to be a one-club man.

Perhaps more tellingly, Kane spent time speaking to every member of the Spanish media after Spurs' recent 1-1 draw at the Bernabeu. A charm offensive?

The Londoner signed a reported £100,000-a-week contract last year to keep him tied to Spurs until 2022, but former England defender Danny Mills says Kane's future is not about money.

"Harry has got where he is today because he is ambitious and because he wants to improve," BBC Radio 5 live analyst Mills said.

"He is going to want to win trophies and at the end of his career he wants to say 'I won the Champions League and I won this amount of titles'. That's the pull. That's why he will leave."

quote Harry strikes me as a bit of a home boy and being away from where he has been his whole life will be a shock to him Jermaine Jenas Former Spurs team-mate

Another key factor is whether he would want to uproot his family - fiancee Kate and 10-month-old daughter Ivy - from their home in London if he were to move to a foreign club.

Bringing up a child in a country where you don't speak the language, don't have a home and don't have your family around you to provide a support system is difficult. Ask Michael Owen.

The former England striker moved to Real Madrid from Liverpool in 2004, describing his off-field time in the Spanish capital as a "horror story".

"I envisaged immediately having a lovely house, swimming pool, sitting out in the sun, and when I got back from training I would be playing with the two-year-old in the garden. We were not prepared for a long time in a hotel," Owen said.

"Madrid did plenty to help us but they put us in a hotel for businessmen for five months; we had a lovely room, but it was not conducive to playing happy families."

Calderon says the club would provide "all the support a player needs", but Jenas believes adapting to Spanish culture could "rock Harry a little bit".

"He strikes me as a bit of a home boy and being away from where he has been his whole life will be a shock to him," the former England international said.