German giants Bayern head to Emirates Stadium on Wednesday in blistering form - unbeaten in 46 Bundesliga outings and in the middle of a 13-match winning streak.
They are also the reigning European champions and sent Arsenal packing en route to claiming continental glory in 2012/13.
Mertesacker is aware of the size of the task facing the Gunners in the last 16 of this season's competition, but believes Arsene Wenger's side - who claimed a notable 2-0 victory at the Allianz Arena 12 months ago - are capable of rising to the challenge.
The Germany international said in the Daily Mirror: "We have to go for two perfect games against them.
"We know we can beat them now, so maybe mentally we are in a better condition than last year.
"We respected them too much in the first leg then (a 3-1 defeat), so it was too easy for them.
"Maybe we have learned something from those lessons and will do better this time.
"Now we have another chance, and an opportunity to beat the champions. We want to achieve something exceptional this season, so we have to beat the best.
"That is not only Manchester City and Chelsea (in the Premier League), that is Bayern Munich in the Champions League."