Roberto said he thought he was on offside position.
Barcelona pulled off the greatest comeback in Champions League history when they beat PSG 6-1 to win the tie 6-5 on aggregate.
Match-winner Sergi Roberto admitted he wasn’t sure if his decisive injury-time goal would count.
He told reporters, “I’ve thrown everything. I didn’t know if I was onside. I’m very happy.
“I threw myself on the ground and I saw the goalkeeper [Kevin Trapp] didn’t stop it.”
Barca were 2-0 up at half-time through a Luis Suarez strike and a Layvin Kurzawa own goal.
Lionel Messi added the third early in the second half from the penalty spot to increase their hope of advancing.
But the Catalan fans became quiet when Edinson Cavani scored the much needed away goal in the 62-minute.
Neymar free kick and penalty minutes in two minutes set the stage for Roberto’s 95th-minute strike to complete the rally and send Barca through to the quarterfinals.
Roberto added, “They say the fans are one more player, but today they were 10 more.
“In the end, this is also for them. Now to celebrate and think about the league game [against Deportivo La Coruna on Sunday.”