Shkodran Mustafi praised Arsenal's never-say-die attitude as they beat Southampton 2-1 at Emirates Stadium on his debut.
The Germany international made a big-money move from Valencia last week, but his new side fell behind to a Petr Cech own goal in the first half on Saturday.
However, with Laurent Koscielny soon equalising, and Santi Cazorla netting a penalty in the final seconds of stoppage time, Mustafi was delighted to see Arsenal fight back and earn all three points.
"If you don't concentrate for 90 minutes, you lose points," he said. "So we concentrated and we were in the game until the end, and that's what gave us the win."
And Mustafi added that winning the game meant more to him than making his Arsenal bow, although he appreciates the reception he has been afforded in north London.
"I'm happy for the three points, first of all," he added. "But I'm also happy with how the supporters have received me here and how the team have made me feel part of it."
Mustafi played the full 90 minutes, while fellow debutant Lucas Perez was withdrawn in the second half for Olivier Giroud.
