With Laurent Koscielny, Shkodran Mustafi, Gabriel and Kieran Gibbs all unavailable in a defensive selection crisis, the former Germany international was named in the starting line-up by Arsene Wenger for the first time since April 2016.
Many observers wrote off Arsenal's chances before the game due to Mertesacker's impending involvement, but the 32-year-old used that negativity as motivation and went on to produce an assured display in his side's 2-1 victory.
He told reporters: "You can always say it was a first start of the season and first of being captain.
"But I went into the game saying to myself, 'There is nothing to expect, everyone has written me off already' and I went through my normal routine – 15 years and you never forget.
"You know what you have achieved and what you have been through. I trusted myself in a good way.
"I expect myself to perform at that level every single week. I don't know if I'm capable but I have done it for 15 years. The more people that write me off, the stronger I get. That's my feeling."
Mertesacker was quick to thank Wenger for the faith he had shown in selecting him as he described his emotions after a rollercoaster week.
"Two weeks ago I was on holiday – I didn't expect to play," he said.
"Everyone trusted me and supported me throughout the season when I was not playing and the manager gave me the opportunity.
"Our team had three centre-backs out and he could have gone small but he went with the big fella and that is something I need to give him credit for because I haven't played a lot.
"I just trained, always with the same focus and mentality because in football things change quickly.
"I'm just blessed for this opportunity. For the trust from my team-mates and my manager because being sidelined for such a long time, I suffered a lot this season because you want to contribute on the pitch.
"To be able to do that was a very proud moment for myself and to lead the team out for the first time officially as captain is great.
"I think we have shown great support in him [Wenger] as well and for his trust in us. We have shown with that performance, it's a statement. This is a very exceptional team."