Key battles, players to watch in the Champions League

Business is about to pick up.

The Champions League group stages did not disappoint with a record 308 goals scored - and Europe's elite club competition returns with the start of the knockout stages.

All four English teams - holders Liverpool, runners-up Tottenham, Chelsea and Manchester City - progressed to the last 16, with last season's finalists both in action this week.

Paris St-Germain against Borussia Dortmund has been described as "the tie of the round", so will this finally be the French side's year? And can Dortmund's teenage star Erling Braut Haaland continue his sensational goalscoring spree?

European football experts Raphael Honigstein, Julien Laurens and Kristof Terreur discuss the first set of games on BBC Radio 5 Live's Euro Leagues podcast.

Champions League last-16 first legs Tuesday, 18 February Wednesday, 19 February Tuesday, 25 February Wednesday, 26 February Atletico Madrid v Liverpool Atalanta v Valencia Chelsea v Bayern Munich Lyon v Juventus Borussia Dortmund v Paris St-Germain Tottenham v RB Leipzig Napoli v Barcelona Real Madrid v Manchester City

'The most attacking teams in Europe'

PSG have won the Ligue 1 title in six of the last seven seasons and, as expected, are top of the table once more, 10 points clear of second-placed Marseille.

Thomas Tuchel's side were highly impressive in Group A, winning five and drawing one of their six games to come top ahead of 13-time European champions Real Madrid.

They face a Dortmund side that came second in Group F behind Barcelona, but knocked Serie A leaders Inter Milan into the Europa League.

"I think this is the tie of the last 16," says Laurens. "I can easily see a 4-3 Dortmund in the first leg and 5-3 PSG in the second leg. They are probably the best two attacking teams in Europe right now. But they are also not the best at defending."

Lucien Favre's men had been top of the Bundesliga but have fallen four points off the pace with two defeats in their last six games, including a 4-3 loss at Bayern Leverkusen.

"Dortmund are not even doing their best to implode, they just implode all the time it seems," says Honigstein. "They had another horrific result and performance in the Bundesliga against Leverkusen.

"It is the sort of result and sort of vulnerability in defence that will not win you titles and will make it very difficult to knock out one of the favourites.

"There are so many issues in defence - clearly something tactical is wrong, they've been ongoing for one and a half years. I think they have pretty good players, on paper it shouldn't be as bad. They make silly mistakes."

Can Haaland and Sancho stop PSG?

Erling Haaland and Jadon Sancho have both been prolific this season

Norwegian Haaland scored a remarkable eight goals in five Champions League games for RB Salzburg and joined Dortmund for £17.1m in the January transfer window.

He then netted nine goals in his first six games for the German side, taking his total to 33 in 28 games this season.

Haaland now pairs up with fellow 19-year-old Jadon Sancho, who earlier this season became first ever player under the age of 20 to score 25 career Bundesliga goals.

So can the teenage duo lead the club to success?

"Dortmund are a club that are really frustrated," says Honigstein. "They see the potential of the squad, especially up front. I don't think we will see the likes of Sancho and Haaland playing together for many more months let alone years.

"But for the moment they are all there and, with the ball, they can be breathtakingly brilliant. But what is the point if you are going to concede goals.

"PSG have their own issues, some tactically, some mental and historical but Dortmund can't defend against average Bundesliga sides, so how can they defend against Neymar and the like?

"Unless they completely overwhelm PSG in the first leg, which is not impossible. Right now there is very little to suggest they can keep one tight game, let alone 180 minutes."

PSG have an issue with Brazilian forward Neymar, who has been suffering with a rib injury, but has been named in the squad for the first-leg on Tuesday.

Laurens adds: "My hands are sweating already. Neymar's fitness is the first thing. We thought they were just preserving him but now seems more serious than we thought. He has been training though, I don't know if they are bluffing.

"It is not the situation they wanted because in the last two seasons he missed a crucial Champions League match and they must want him fully fit."

Simeone's last stand?

Jurgen Klopp's Liverpool are looking strong to make it three finals in a row after coming top of Group E and face an Atletico Madrid - runners-up behind Juventus in Group D - at the Wanda Metropolitano, where the Reds lifted the trophy for the sixth time last year.

Klopp's side are running away with the Premier League title, dropping just two points all season, while Atletico are fourth in La Liga, 13 points behind leaders Real Madrid.

"Atletico are not the Atletico team they were before, when they had that team of warriors - all fighters who were typical Diego Simeone players. They had a nasty side," says Terreur.

"I watched them play Real Madrid and it was a very boring game, you see a team that is not a team any more."

Atletico had to rebuild in the summer after key players Antoine Griezmann, Lucas Hernandez, Rodri, Diego Godin, Filipe Luis and Juanfran all departed.

"I don't think they can sack Simeone," says Laurens. "He presents so much to that club. He might walk out himself if he thinks he reached the end. But this was always going to be a transitional year anyway, because so many big players left last summer.

"It was always going to take time for Simeone to make what he had last time with these players. Maybe he is finished and maybe he is too old school to succeed now. I would love to have seen this game three years ago.

"No, no way this Atletico side can trouble Liverpool."

Wednesday 19 February

Atalanta v Valencia

Debutants Atalanta progressed after coming second in Group C behind Manchester City, despite losing their opening three games, while Spanish side Valencia came top of a tight Group H ahead of second-placed Chelsea.

"Even if you are not a neutral, you are pulling for Atalanta because you want to play them in the next round. This is one of those strange pairings that happen," says Honigstein.

"If you are a club like Manchester City or Real Madrid, you are thinking the next game could be easier than the last 16 game. This is a game people might look at with ulterior motives, Atalanta being a newbie, the Cinderella story and playing exciting football. They will entertain and bring us something different."

Tottenham v RB Leipzig

Spurs recovered from a 7-2 home thrashing by Bayern Munich to come second in Group B behind the Bundesliga champions, while German opponents RB Leipzig topped Group G ahead of Lyon.

"Most people would have Leipzig as favourites," says Honigstein. "Two words explain that: Harry Kane [who is injured].

"[Leipzig] have depth and we now find out how good they are internationally. They are still a bit immature and not a side that can go into games knowing they will dominate, all the signs of a team that is growing."

The remaining fixtures

Tuesday 25 February

Chelsea v Bayern Munich, Napoli v Barcelona

Wednesday 26 February

Lyon v Juventus, Real Madrid v Manchester City