Chelsea pushed forward and Cesar Azpilicueta saw his effort blocked after a fine run by Willian. Then the Brazilian was felled on the edge of the area, but German referee Felix Brych waved play on.
But the calf injury that had threatened his participation in this game struck Costa, as he limped off. It was a decisive blow. On went the youngster Bertrand Traore but, without their talisman, Chelsea seemed to wilt.
Motta sent Di Maria away down the left, and his low cross found Ibrahimovic racing in to crash the ball home from six yards.
Chelsea’s hearts were broken. The big Swede had said before the match that he was not finished, he was only warming up – and that PSG would definitely one day win the Champions League. With a goal in the first leg, an assist and a strike last night. Ibrahimovic proved his point. Bizarrely, Hazard had swapped shirts with Di Maria at half time.
The Belgian, so disappointing for much of the season, then motions that he wanted to come off in the closing stages and limped so, going straight down the tunnel. That was emphatically not the Chelsea spirit of old.
Chelsea (4-2-3-1): Courtois; Azpilicueta, Cahill, Ivanovic, Kenedy; Fabregas, Mikel; Pedro, Willian, Hazard; Costa. Booked: Fabregas. Goal: Costa 27.
PSG (4-3-3): Trapp; Marquinhos, Thiago Silva, David Luiz, Maxwell; Rabiot, Thiago Motta, Matuidi; Di Maria, Ibrahimovic, Lucas. Booked: Rabiot, Motta. Goal: Rabiot 16.
Referee: Felix Brych (Germany).