PARIS — Zlatan Ibrahimovic waved his hands in the air. Ángel Di María fell to his knees and swiped at the ground in frustration. Laurent Blanc shook his head.
Paris St.-Germain beat Chelsea, 2-1, on Tuesday night, but it might have been difficult to tell at the final whistle. The home team was, to be sure, pleased to have a slight advantage after one leg of this two-game, round-of-16 matchup in the Champions League. But there was also a sense of frustration — regret, even — that the margin was not wider.
On a night when P.