The defender feels the Blaugrana did enough to win Tuesday's encounter, but the Atletico goalkeeper proved to be too much of an obstacle
Diego gifted Atleti the lead after 56 minutes of play with a superb long-range strike, before Neymar made it 1-1 with 20 minutes to go.
Barca then got a number of chances to emerge victorious, but Courtois proved to be too much of an obstacle for the Spanish champions as they had to settle for a 1-1 draw.
"Atletico have a great team and their players can really do damage," Bartra told reporters.
"We competed against a very competitive side and we had clear chances to make it 2-1, but because of Courtois we’re leaving with a draw.
"Even as much as they pressed and tried to take the ball off us, I believe we created the most and the clearest chances to win it.
"We’ll go to the Vicente Calderon to win. If we play the same way we played on Tuesday, we’ll have our chances to win at the Calderon."
The second-leg in the Spanish capital takes place on April 9.