Atalanta go top of Group F thanks to their 1-0 win over Young Boys.

United could find themselves four points off second place if they lose today.

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Just one more bit from our friends at Gracenote...

You may well have seen that FC Sheriff Tiraspol beat Real Madrid last night. Well, that was the biggest shock in the Champions League since the launch of the Euro Club Index by Gracenote and Hypercube in 2010. The chance of a win for the team from Moldova - who were ranked 175th among Europe's top-flight teams - was estimated at 1.4%.

The previous biggest Champions League shock had been Celtic's 2-1 win against Barcelona in November 2012. That had a 7.1% chance of happening.

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Manchester United suffered a setback on matchday one, losing to the weakest team in Group F, Young Boys. United's chance of reaching the last-16 has therefore dropped to 58% according to the Euro Club Index. Any result other than a win against Villarreal this week is likely to further reduce United's chance of progress.

Simon Gleave
Head of sports analysis, Nielsen Gracenote

Image source, Gracenote

Chelsea were drawn in a relatively straightforward group and were given over 90% chance of reaching the knockout phase by the Euro Club Index, external before a ball was kicked. Victory against the third best team in Group H, FC Zenit, has put Chelsea amongst a select group of four teams (Bayern Munich, Real Madrid and Manchester City are the others) whose chance of playing in the last-16 is already at least 96%.

Ashley Young
Aston Villa's former Man Utd winger on BBC Radio 5 Live

The leaders are there – Cristiano Ronaldo has been around the block and won everything there is to win at the club. [Raphael] Varane’s one as well. Harry Maguire’s there, you've got [Edinson] Cavani and Bruno Fernandes has taken on the mantle. But then you look and you think, 'they haven’t won anything'.

The squad Ole has inherited now, it’s about time that they started putting the mantle down and bringing success back to that club. The club is built on success and that’s what has to happen from now on.

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It has needed a penalty shootout to separate these two sides in any way in the past.

After four successive 0-0 stalemates, the 1-1 draw in last season's Europa League final was followed by a shootout won by the Spanish side.

If you were looking for some kind of hope that this game won't be a dour draw then I'm afraid I can offer little right now. Villarreal have drawn five of their six games in La Liga this season, with four of them being 0-0. They also drew their opening Champions League game, although this was a far more exciting 2-2.

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When Max Allegri returned to Juventus in the summer, everyone in Turin expected his arrival would coincide with an immediate return to the winning ways of his first trophy-laden period in charge of the club.

He won five straight Serie A titles before leaving in 2019 by mutual consent.

His return was essentially an admission the club had wasted the two years since he left.

But they had dropped into the relegation zone before back-to-back 3-2 wins over Spezia and Sampdoria.

Read why it's not gone too well here.

Shamoon Hafez
BBC Sport at Old Trafford

Only a few hundred in at the moment but a huge cheer has gone up from those in attendance.

It's in the direction of United boss Ole Gunnar Solskjaer, who emerged from the tunnel for his pre-match duties.

Certainly hasn't lost the backing of the home supporters... yet.

Stuart Mitchell: The team is the right one for Man Utd. They don't need a double pivot, or shouldn't do. United should really be scoring 3 or 4 tonight but I doubt anyone expects anything else than a turgid slow performance again.

Peter: Re Micah 19:08 .... You are totally right. However you have to remember that for most football fans everything is either 100% great or 100% an absolute disaster – hence OGS's dilemma.

Ashley Young
Former England winger on BBC Radio 5 Live

The way [United] have started the campaign is not the way they wanted to get off. The way that this last week has gone as well, the defeats in the Carabao Cup and against Aston Villa – it adds pressure to the game tonight.

Your home games in the Champions League are always vitally important. You want to get three points when you’re at home. They need to get the fans behind them and go and win the game.

Shamoon Hafez
BBC Sport at Old Trafford

We're only in September and this is only the second Champions League group game but you feel this is a big game for Manchester United and manager Ole Gunnar Solskjaer.

United come into the game on the back of two limps defeats at Old Trafford - knocked out of the Carabao Cup by West Ham last Wednesday and humbled in the Premier League by Aston Villa on Saturday.

Solskjaer has been criticised by fans and pundits including ex-defender Gary Neville for relying on individual brilliance to win matches rather than having a formulated style of play to break down opponents.

The defeat against Swiss side Young Boys in the opener was a disaster and another loss today will edge the Red Devils towards a full blown crisis.

Atalanta have just taken a 1-0 lead against Young Boys - conquerors of Manchester United last time out.

Matteo Pessina turned home a cross from close range with 22 minutes left.

Barcelona make four changes from the side that beat Levante 3-0 in La Liga on Sunday, with Frenkie de Jong, Pedri, Ronald Araujo and Sergi Roberto coming into the side.

Philippe Coutinho, Nicolas Gonzalez, Pablo Gaviria and Oscar Mingueza make way.

They face a strong Benfica side who have won their opening seven league games in Portugal and are captained by former Manchester City defender Nicolas Otamendi.

Benfica: Odisseas Vlachodimos, Jan Vertonghen, Nicolás Otamendi, Lucas Verissimo, Valentino Lazaro, Julian Weigl, João Mário, Alejandro Grimaldo, Roman Yaremchuk, Rafa, Darwin Núñez.

Barcelona: Marc-André ter Stegen, Ronald Araújo, Eric García, Sergiño Dest, Gerard Piqué, Pedri, Sergio Busquets, Frenkie de Jong, Memphis Depay, Sergi Roberto, Luuk de Jong.

Micah Richards
Former England defender on BBC Sport website

Part of the problem for Ole Gunnar Solskjaer is that there is an over-reaction to every Manchester United win - and also every defeat.

That's down to the size of the club and United's recent history, when they won so much. Expectations are so high that when they don't perform there is always going to be a backlash.

The first few weeks of this season have been the perfect example of that - for good and bad.

When United have won games, some people have been talking about how they are going to win the title. But when they lose, it is a total disaster and Solskjaer apparently has to go.

In reality, things are not as extreme either way and, if you look at the top of the Premier League table and see how everyone else has dropped points too, you can see there is no need at all for any alarm bells to be going off at Old Trafford.

Read more here.

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These are tricky times for Manchester United.

They have watched on as their two biggest rivals have lifted the Premier League title in recent seasons, and enviously peered at Chelsea claiming a European crown as they faltered in their own final.

They've spent money to try and bridge the gap. Boy have they spent money. But as yet it hasn't been enough. And last weekend's loss at home to Aston Villa has hinted that despite all the spending, similar failings remain.

So what now? Well, for starters they really do need to win tonight. Especially after the shambles at Young Boys. If they don't, the knives will be sharpened even more for manager Ole Gunnar Solskjaer...

This will be the fifth meeting between Juventus and Chelsea in the Champions League.

The most recent meeting was in the 2012-13 Champions League group stages, with Juve winning 3-0 at home.

Chelsea sacked Roberto di Matteo the next day.

Thomas Tuchel will probably be safe no matter the result tonight...

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Chelsea make three changes from their 1-0 defeat by Manchester City.

Thiago Silva, Hakim Ziyech and Kai Havertz replace Reece James (injury), N'Golo Kante (Covid) and Timo Werner (bench).

Chelsea: Mendy, Christensen, Silva, Rudiger, Azpilicueta, Jorginho, Kovacic, Alonso, Ziyech, Havertz, Lukaku. Subs: Arrizabalaga, Werner, Loftus-Cheek, Bettinelli, Chalobah, Saul, Barkley, Hudson-Odoi, Chilwell, Sarr.

Three changes for Juventus too.

Wojciech Szczesny comes back into goal and Danilo and Adrien Rabiot are also in the team.

Forwards Paulo Dybala and Alvaro Morata are both injured, while keeper Mattia Perin drops to the bench.

Moise Kean is on the bench with Juve option for no recognised striker.

Juventus: Szczesny, Danilo, Bonucci, De Ligt, Sandro, Cuadrado, Bentancur, Locatelli, Rabiot, Bernardeschi, Chiesa. Subs: De Sciglio, Chiellini, McKennie, Kean, Pinsoglio, Rugani, Perin, Kulusevski.

Shamoon Hafez
BBC Sport at Old Trafford

A repeat of last year's Europa League final and Ole Gunnar Solskjaer has revenge on his mind.

The Manchester United manager makes four changes to the side that lost here against Aston Villa on Saturday.

Three of those are enforced in defence with skipper Harry Maguire and Luke Shaw injured, while Aaron Wan-Bissaka is suspended.

Diogo Dalot, Victor Lindelof and Alex Telles come in with Jadon Sancho replacing Fred the other change.

Man Utd XI: De Gea, Dalot, Varane, Lindelof, Telles, McTominay, Pogba, Fernandes, Sancho, Greenwood, Ronaldo.

Villarreal suffered a blow before the game as forward Gerard Moreno, who scored in that Europa League final in May, is out injured, while former Arsenal midfielder Francis Coquelin is suspended.

Veteran Spanish defender Raul Albiol skippers the side and former Spurs players Juan Foyth and Etienne Capoue both starting. Big money summer signing Arnaut Danjuma, brought in from Championship side Bournemouth, is also in.

Villarreal XI: Rulli, Foyth, Albiol, Torres, Moreno, Parejo, Capoue, Danjuma, Trigueros, Pino, Alcacer.