Antonio Conte’s side had taken a 62nd-minute lead through Willian’s 25-yard strike before Messi profited from an Andreas Christensen mistake to convert from Andres Iniesta’s pass, ending his wait for a goal against Chelsea at the ninth time of asking.
The Blues now face a huge uphill task in the return game on 14 March to avoid a European exit which would only heighten speculation over Conte’s future as manager.
Apprehension permeated the air at kick-off, perhaps in part a consequence of Conte’s cautious team selection, opting to leave Alvaro Morata and Olivier Giroud on the bench in favour of deploying Eden Hazard as a false nine.
The Belgian flashed a fifth-minute shot off-target from the edge of the box as Chelsea held their own in the opening exchanges before Barcelona gradually asserted control.
Messi created some space for himself just outside Chelsea’s box and stood up a superb cross towards the far post where Paulinho was lurking unmarked. However, the Tottenham midfielder could only steer a tame header wide.
The visitors racked up 75 per cent possession by the midway point of the first-half yet it was Willian who twice came closest to scoring before the interval.
The Brazilian collected a pass from Hazard 25 yards out before driving past Sergio Busquets and sent a curling effort against Marc-Andre ter Stegen’s left-hand upright with the Barcelona goalkeeper rooted to his line.
He tried to beat him from a similar distance – but to the other side – eight minutes later only with the same outcome, as the ball cannoned back off the woodwork.
Belief surged around west London as despite their dominance, Barcelona had failed to register a shot on target in the opening 45 minutes – the first time they had done so since in a Champions League game since facing Arsenal in February 2016.
Willian’s personal mission to find a way past ter Stegen succeeded on his third attempt. After a long spell of territorial yet somewhat sterile dominance from Barcelona, Chelsea broke and earned a corner through Cesc Fabregas’ deflected shot.
The resultant set-piece was delivered to Willian and with the most densely-packed defence to beat of his three chances, he found a way through the forest of legs and inside ter Stegen’s near post.
The game returned to a familiar pattern – Barcelona probing while Chelsea looked to break at pace – but the Catalan giants needed a helping hand from Christensen to restore parity.
Christensen hit a poor pass across his own area which Iniesta picked up in a dangerous position inside the box. He waited to pick the right pass, typically, feeding Messi in space and he converted first-time before speeding off to celebrate in front of Barca’s travelling support.