Top Winners and Losers After Wednesday's Champions League Matchday 5 Results

Chelsea have another young star in the making in the form of 19-year-old defender Reece James, but the Blues still haven't qualified for the last 16 of the 2019/20 UEFA Champions League because of problems at the back.

Specifically, James couldn't mask deficiencies at left-back during a 2-2 draw with Valencia at the Mestalla Stadium in Group H. Both Cesar Azpilicueta and Emerson Palmieri found themselves victimised by Rodrigo Moreno to emphasise the Blues' problems at the position.

Napoli don't have Chelsea's woes in defence, but the Serie A outfit will have trouble keeping Kalidou Koulibaly a the club beyond the next transfer window. The burly centre-back would have whetted the appetites of suitors with an imperious display during a 1-1 draw with Liverpool at Anfield, a result enough to ensure the holders are left waiting to qualify from Group E.

Barcelona are already through and can continue to rely on the brilliance of Lionel Messi. Yet on a record-setting night for the Argentinian, Antoine Griezmann's late goal may have been the biggest positive from the 3-1 win over Borussia Dortmund.

The Frenchman has been struggling to fit in since swapping Atletico Madrid for Barca, but he may finally be building a genuine rapport with Messi.

Winner: Reece James

Add James' name to the list already including Tammy Abraham, Mason Mount, Fikayo Tomori and Callum Hudson-Odoi. Chelsea's academy has yielded another gem judging by James' assured performance against Los Che.

The teenager was given a thankless task on the edge of a back three regularly exposed by Valencia's quality in wide areas. Even so, James acquitted himself brilliantly in both phases of the game.

His strength, speed and aggression made James invaluable to a defence also undermined by the erratic performance of fellow centre-backs Kurt Zouma and Andreas Christensen:

It wasn't just about defending for James, though. He also proved himself an asset going forward, showcasing energy, technique and vision to add impetus to a side built to own the ball and boss the final third:

Frank Lampard won't like what he saw from the rest of the Chelsea defence, but he will have left Spain believing James is ready and able to play a bigger role for a developing unit.

Loser: Chelsea's Left-Back Options

There was no mystery about how Valencia created so many chances against the Blues. The strategy was a simple one, get the ball to Rodrigo on the right and watch him torment the Chelsea left-back.

Had it not been for the Spain international's curious profligacy in front of goal, Chelsea would have been on the end of a humbling defeat thanks to their left-backs:

What was most surprising is how a decorated veteran like Cesar Azpilicueta struggled. The 30-year-old couldn't anticipate the timing of Rodrigo's runs and usually lost the guessing game about whether the forward would pull wide or drift infield.

He was once the most reliable and versatile defender in the Blues' ranks, but Azpilicueta is playing like a shadow of his former self. His decline is forcing Lampard to rely on players who have been shaky for a while.

Lampard hasn't trusted Marcos Alonso too often, but he may soon feel the same way about Emerson after the former AS Roma man was also exploited once he entered the fray as a 72nd-minute substitute for Jorginho.

A talent void at left-back is undermining the whole of a suspect Chelsea defence. It's the main reason Lampard and Co. are left sweating on qualification.

Winner: Antoine Griezmann

Griezmann and Messi aren't supposed to be on the same page. Look a little closer, though, and signs of genuine chemistry may be forming.

Messi's slide-rule pass for Griezmann's 67th-minute goal at the Camp Nou showed what is possible when these two click. The move was the perfect fusion of Messi's creative instincts and cultured passing, along with Griezmann's pace and perceptive movement.

Moments like these have been rare since Griezmann became a member of the Blaugrana. The fact he started on the bench against Dortmund, for a game with qualification at stake, only underlined how far the 28-year-old's stock has fallen.

Yet if link-ups like this one become more common, Barca's path to winning this trophy for a sixth time will be unchallenged.

Loser: Napoli's hopes of keeping Koulibaly beyond January

Napoli should set their dream fee for Koulibaly now because president Aurelio De Laurentiis will surely be fielding a host of offers for his rock at the back ahead of the winter window.

Keen parties ought to be putting together bids immediately after the way Koulibaly frustrated Liverpool on Merseyside. The Senegal international bullied the Reds in the air:

He also stayed quick on the deck, alert to danger and agile enough to recover and snuff out any threat that got through:

This was a statement performance from a 28-year-old entering the prime of his career. Europe's biggest names can no longer ignore the impact Koulibaly would make at the highest level.

Manchester United have a longstanding interest after bidding £91 million last summer. Meanwhile, Barcelona have also been credited with interest, along with Manchester City and Real Madrid.

Any one of those clubs would be wise to get the ball rolling early for a defender talented enough to fetch a bigger fee than the world-record sums Liverpool paid for Virgil van Dijk and United forked out on Harry Maguire.