A long-range effort from Diego sent Atletico into the lead at the Camp Nou, but Neymar's curling finish 20 minutes from time levelled the scores in the European tie.
"As far as our goal is concerned, Neymar has that talent, that quality. With just one moment, one move, he can turn the game and the result," Iniesta told reporters.
"We are delighted with his goal and now we have to ensure that it becomes significant in turning the tie our way."
The second leg at the Vicente Calderon will take place next week.