Lionel Messi scored his first goal against Chelsea to earn Barcelona a 1-1 draw in the first leg of their Champions League last-16 clash at Stamford Bridge on Tuesday.
Messi had not found the net in eight previous matches against the Blues, but he punished Andreas Christensen's misdirected pass across his own box in the 75th minute to grab an away goal for Barca.
Willian had put Chelsea ahead in the 62nd minute with a brilliant curling strike, having also hit both posts in the first half.
Chelsea: Courtois (6), Rudiger (7), Alonso (7), Moses (7), Christensen (5), Azpilicueta (7), Fabregas (6), Kante (7), Pedro (6), Willian (8), Hazard (6)
Subs: Morata (5), Drinkwater (5)
Barcelona: Ter Stegen (6), Sergi Roberto (6), Pique (6), Umtiti (6), Alba (6), Busquets (7), Paulinho (6), Rakitic (6), Iniesta (6), Messi (6), Luis Suarez (5)
Subs: Vidal (5), Gomes (5)
Man of the match: Willian
But the Premier League side must now score in the return leg at the Nou Camp on March 14 if they are to progress to the quarter-finals.
Chelsea, who started with Eden Hazard as a false nine and Alvaro Morata and Olivier Giroud on the bench, had looked as though they were going to take a first-leg advantage after blunting Barcelona's attacking threat.
While the visitors dominated possession in the first half, it was Chelsea who went closest to scoring.
Hazard flashed an early shot over the bar while Willian hit the post twice with efforts from outside the box, striking the right-hand upright in the 34th minute and then hitting the left post with a snap-shot in the 41st minute.
Hazard also volleyed over the bar before half-time, with Barca's only chance falling to Paulinho in the 16th minute when he headed wide.
The game continued in the same pattern in the second half but it was Chelsea who broke the deadlock when Willian finished brilliantly, curling a shot into the bottom corner from the edge of the box.
The goal looked as though it might be decisive on the night as Barcelona struggled to find a way through Chelsea's well-organised defence.
But Barca seized upon Christensen's poor pass across his own box, with Andres Iniesta skipping away from Cesar Azpilicueta's diving tackle and then pulling back for Messi to finish expertly into the bottom corner.
Hazard started as a false nine for Chelsea with Morata and Giroud on the bench. Alonso returned from injury and Cahill was on the bench. Barca were unchanged from their win over Eibar on Saturday, with Coutinho unavailable as he is cup-tied.
- Barcelona have conceded in each of their seven visits to Stamford Bridge in the Champions League (W1 D2 L4), with their only win coming in February 2006 (2-1)
- That win for Barcelona was the last time that Chelsea lost against the Spanish side, with the Blues unbeaten in their last eight Champions League games (W2 D6).
- Six of Willian's nine Champions League goals for Chelsea have come from outside the box (67%).
- Chelsea are the 71st club that Lionel Messi has scored against for Barcelona - he has only failed to score against 11 clubs that he has faced.
- Lionel Messi has now scored at least one goal in exactly half of his appearances in the Champions League (61 games scored in, 122 appearances).
- Luis Suarez has now failed to score in the last 881 minutes of play in the Champions League, his longest drought in the competition. His last goal dates back to March 2017 against PSG.
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Antonio Conte: "I think we were very close to playing the perfect game. I think we paid dearly for one mistake. But as you know very well, against this type of player - like Messi, like Iniesta, like [Luis] Suarez - if you make a mistake you pay. It's a pity because tonight at the end of the game we are disappointed with the final result."
Ernesto Valverde: "The good thing is that we managed to get an error out of them and we got an equaliser. We go back to the Camp Nou happy. I think the equaliser was very important. They might be happy with the result and we have to be respectful of their style of play. They pressed us very high and made life difficult for us."
Man of the match - Willian
Willian continued his fantastic recent form with another standout display. He twice went close to scoring in the first half with shots that hit the post and left Marc-Andre ter Stegen rooted to the spot.
But it was third time lucky as he shimmied away from Sergio Busquets in the 62nd minute and curled a fantastic effort into the bottom corner.
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Chelsea travel to Manchester United on Sunday and then go to Manchester City a week later, with both games live on Sky Sports. Barcelona host Girona in La Liga on Saturday and then go to Las Palmas on Thursday, March 1, with both fixtures again live on Sky Sports.
The second leg takes place at the Nou Camp on Wednesday, March 14.