The visitors produced a resilient defensive display at Etihad Stadium, restricting their opponents to just four efforts on target.
Mertesacker was pleased with the spirit shown by the whole team, and feels Arsenal have learnt from losing 6-3 in last season’s corresponding fixture.
“We didn’t rush ourselves to do anything,” he said. “We stayed calm over the whole 90 minutes and just dropped a bit deeper.
“It’s very unusual for us, but we learned, especially from last season. I would say it was a mature performance.
“We don’t have to talk too much – it was just one game, but it was a good response.
“Every player was up for proper defending from front to back. I think we have to praise the whole unit,” he told arsenal.com