In front of a raucous Selhurst Park crowd, Mateta became Palace's first ever European goalscorer, after heading in Will Hughes' effort at goal nine minutes after the break.
It was enough to give Palace a precious lead to take into next week's away leg, with the winning side on aggregate advancing to the league phase.
And the French forward was happy to write himself further into club folklore with the historic goal.
"I'm very happy to be the first player to score for Palace in a European cup [competition]," Mateta told Channel 5. "I saw the ball in the box and I did my job.
"I was ready if the ball came to me, to touch it and to score. I got into the right body position to the goal, I hoped to score – and yes very happy [I did].