Champions League: Tottenham v Barcelona Date: 3 October Kick-off: 20:00 BST Venue: Wembley Stadium Live text on the BBC website and commentary on Radio 5 live

Guillem Balague will be writing a regular column throughout the season and also appearing every Thursday on BBC Radio 5 live's Football Daily podcast, when the focus will be on European football.

You can download the latest Football Daily podcast here.

Few people know better than Mauricio Pochettino that there is never a 'good' time to face Barcelona.

Even so, the Catalans' current form suggests the timing of Wednesday's Champions League group match is as good as it's ever going to get for the Tottenham boss.

After just seven La Liga games, Barcelona have already dropped seven points. They had only dropped six by the halfway point last season.

They are without a win in three matches. A defeat at lowly Leganes a week ago was followed by a tame home draw against Athletic on Saturday.

What's going wrong at Barcelona?

Three recent errors by Spain defender Gerard Pique have led to opposition goals

Two points out of a possible nine in the league and eight goals conceded in their past seven games suggests a vulnerable team way short of their best form.

Much has been made of uncharacteristic mistakes by centre-back Gerard Pique, with three errors in recent games leading directly to opposition goals. But while he certainly needs to improve his intensity and concentration, Barca's problems go a lot deeper than that.

They are struggling to maintain pressure high up the pitch, and with Ivan Rakitic playing in a more advanced role, the pivotal Sergio Busquets is cutting an isolated figure further back in midfield.

And there is a deeper problem. Too often this season their attacks have been more individual than collective and sometimes too direct. When Barcelona attack as a unit they defend as one as well - but right now, when they lose the ball, there are often big gaps between defence and midfield. Opponents have been exploiting this space.

There is also a lack of strength in depth, with a second string not of the required standard and not making a sufficient impact. OK, trying to fill the boots of the likes of Lionel Messi and Busquets is probably the toughest gig in world football, but, even so, Barca have certainly spent big to bolster their squad.

Philippe Coutinho, bought from Liverpool for £142m in January, works wells enough in an attacking role, but the club's midfielders require a more patient ball distribution and the Brazilian's defensive work needs to improve.

Ousmane Dembele, who joined from Dortmund for £135.5m in August 2017, is not settling in as well as he could. The France forward is struggling with the language, is shy and surrounded by his own people all the time. He was certainly not helped by the bad injury he suffered at the beginning of his Barcelona career.

To his credit, he has scored five goals so far this campaign, but he does not understand enough of the Barca style to help the fluidity of the game or to take the right decisions at key moments.

Malcom, Arturo Vidal, Arthur and Clement Lenglet - all arrived in the summer; all remain on the periphery.

At the same stage of last season Barcelona had seven successive league victories and had conceded just twice. True, they are top of the league on 14 points - but that is the lowest number to head the table at this stage for 25 years.

The next five games for Barca will probably go a long way to defining their season: away to Tottenham and Valencia and then at home against Sevilla, Inter and Real Madrid.

Will Pochettino end up at Barcelona?

Mauricio Pochettino (left) has never faced Barcelona as Spurs boss - with Espanyol he won once, drew three and lost five. That said, he still managed to take more points off Pep Guardiola's Barcelona than any other La Liga manager

Pochettino managed Barcelona-based Espanyol from 2009 to 2012, before moving to Southampton and was a player for them before that.

The Argentine knows Barca president Josep Maria Bartomeu socially and the two men were spotted in the same restaurant in the city last year - which set a lot of tongues wagging.

The Barcelona president has known Pochettino for more than a decade and their kids have gone to the same school. Bartomeu has numerous business interests and partly helped to redevelop the harbour in Southampton when Pochettino was in charge there.

And it is true that when the Pochettino family look for a rest from their busy schedule it is Barcelona where they feel they have their European roots.

But Pochettino would no more manage Barca than he would contemplate joining Tottenham's north London rivals Arsenal.

And anyone thinking that current boss Ernesto Valverde is in danger of losing his job might be a little hasty.

A couple of recent briefings from the club have led the local media to wonder whether the board are 100% convinced - even though the official line is that the Spaniard is the right man to lead the team.

He has been accused of being too conservative with substitutions, of not getting the best out of the new players, of not rotating enough in the first few games - and now of rotating too much.

And the humiliating quarter-final defeat by Roma in last season's Champions League - losing 3-0 away after a 4-1 win at home - is a stick constantly used to beat him with.

But Messi, now the captain, has positioned himself very much on Valverde's side. After Saturday's disappointing 1-1 home draw with Athletic Bilbao, the manager used strong words with his players and had the backing of his skipper.

Champions League the number one priority

It is a frustrating time for Barca - but Messi is determined to bring the Champions League trophy back to the city

Winning the Champions League once in the past seven years is bad enough, but the fact Real Madrid have won it four times in the past five seasons has made that immeasurably worse.

Even before a La Liga ball had been kicked this season, Messi made his feelings clear when he said the club would "do everything possible" to bring the Champions League trophy back to Barcelona.

"Last season was very good because we won the cup and La Liga, but the Champions League sticks in our throat, especially given the way we were eliminated," the 31-year-old Argentina forward added.

Messi, a Champions League winner in 2006, 2009, 2011 and 2015, is not the only one desperate for success in the competition this season. It matters in the boardroom too.

The Champions League isn't just about the glory, but also very much about the money.

The club expect to generate income of 960m euros (£855m) this season, but more than half of their budget is wages. The Champions League is vital to keep the money rolling in to meet this staggering and ever increasing bill, as well as to attract the type of players needed to win it.

So, although Barca are going through a difficult phase, I would urge caution for any Spurs fans predicting anything other than a very tough test on the wide open spaces at Wembley.

Ultimately, this season Barcelona and Valverde will be judged by what they achieve in the Champions League - and their first XI, fully focused and determined, remain a match for any team.