The fixture was a familiar one for both sides, with the pair having faced each other in the Champions League’s latter stages on several previous occasions.
In fitting with a game of such magnitude, the two sides spent the opening exchanges getting a feel for each other, with neither willing to commit too much too early.
Eden Hazard was the first to try his luck, hammering a left-footed strike just off target after cutting in from the right.
Barca dominated possession for long stages during the first half, but generally it was the hosts who looked the more dangerous in front of goal.
With just 16 minutes on the clock the visitors fashioned their first gilt-edged chance, but Paulinho - preferred in midfield to Andre Gomes - headed wide from 12 yards after being expertly picked out by Lionel Messi.
Despite being an entertaining affair it was a first half of few chances, with Chelsea best efforts coming from Willian, who twice rattled the post with efforts from long range.
At the other end, Gerard Pique failed to take full advantage after his marker slipped to allow him a free header from a corner.
Hazard powered a volley over the bar in the dying embers as the first half ended goalless.
- More Barca possession -
The second half started as the first had finished, with Barca dominating the ball but without any real creative edge.
Andres Iniesta blazed over from range, before Luis Suarez forced a good low save from Thibaut Courtois from a narrow angle after jinking past Cesar Azpilicueta.
However, despite Chelsea barely having a kick for long spells it was they who found the opener.
Cesc Fabregas - playing against his boyhood side for the first time - saw an effort deflected away for a corner on the left, which the hosts took quickly. The ball was worked to Willian on the edge of the box and he duly curled home a lovely finish form 18 yards. Very much a case of third time lucky for the Samba star.
20 February 2018
Given their solid defending up to that point it looked like Chelsea would take a precious lead to the Camp Nou, but it wasn’t to be, with the ‘Blues’ shooting themselves in the foot with just 15 minutes to play.
Andreas Christensen tried to play an ill-advised ball across his own box and Andres Iniesta pounced to get there ahead of Azpilicueta before squaring for Lionel Messi to sweep Barca level from just inside the box and in doing so score his first goal against Chelsea at the ninth time of asking.
20 February 2018
Neither side could find the late goal that could give them control of the tie ahead of the return leg in Catalonia, but Barca's precious away goal gives them the edge ahead of the game at the Camp Nou.