Zlatan Ibrahimovic headed it down, and with the last kick of the match, Blaise Matuidi fired Paris Saint-Germain level.
A slight deflection took it past Victor Valdes, but PSG won't care. They had their equalizer and, with it, some hope to carry forth to Camp Nou next week.
The French side accelerated out of the blocks, but, as ever, it was Lionel Messi who opened the goal scoring with a wonderful finish.
Ibrahimovic squared the score in the second half, but when Alexis Sanchez won a penalty and Xavi Hernandez converted it, Barca looked set to clinch the win.
But in a final twist, Matuidi popped up to keep things even ahead of the second leg.
Here are Barcelona's winners and losers from their night in Paris...