the Parc des Princes in a pulsating first leg, with Blaise Matuidi's stoppage-time shot squirming through the grasp of visiting 'keeper Victor Valdes.
Xavi Hernandez had given Barcelona the lead from the penalty spot in the 89th minute after Zlatan Ibrahimovic had cancelled out Lionel Messi's first-half opener.
Conceding so late on was a blow for the Spanish league leaders, but the two away goals give them the edge ahead of the return.
However, Barca's night was marred by injuries, with centre-half Javier Mascherano being carried off in the second half and Messi not reappearing after the break because of a hamstring injury.
"Messi has a small hamstring problem," said Roura, who appeared before the press after the game despite coach Tito Vilanova returning to the bench for the first time since spending two months in New York undergoing cancer treatment.
"We will find out more about the injury tomorrow (Wednesday)," he added, although Messi appeared to be walking without any trouble as he made his way through the mixed zone after the game.
"Mascherano has a knee ligament injury and will be out for between four and six weeks.
"We will try to ensure that these injuries do not have an impact on the second leg," he added, with the return to come at the Camp Nou next week.
"They are two very important players to us, but we have a big enough squad and we certainly have players who are capable of filling in."
The game itself was marked by some contentious decisions, with Barcelona not happy that Ibrahimovic's strike in the 79th minute was allowed to stand.
They felt that German referee Wolfgang Stark should have disallowed the goal for offside.
"There were decisions made by the referee which could at least be contested," said Roura, who added that he was not surprised by the battling nature of PSG's performance.
"I was not surprised by them at all. We knew they would be direct and physical.
"They have great players so we were expecting a difficult game, but we are confident that we can get through the second leg in front of our own fans."
Ancelotti said that he could not fault his team's performance, but bemoaned Starks's decision to award the visitors a late penalty and admitted that the result leaves his team with a lot of work to do in the return.
"I don't think it was a good result," he said. "We played very well in the first half, but the two goals we conceded were gifts.
"The first goal was a gift to Messi on the edge of the box, and the second was a gift by the referee.
"I don't think it was a penalty, I think (Alexis) Sanchez was looking for the contact from (goalkeeper Salvatore) Sirigu.
"We have experience of him, because he dived when we played them in a friendly in August.
"I am not happy with the result," he added, although the former AC Milan and Chelsea boss believes his team can unsettle Barcelona in the second leg.
"You have to defend against Barcelona, but when you have the ball you will have chances to attack and be dangerous.
"I am confident that we can do something there."