A 4-0 victory over Watford at the weekend kept third-placed Arsenal 11 points behind league leaders Leicester with a game in hand on the Foxes
With Arsene Wenger's men having seven games left, Mertesacker has not given up hope of overhauling the pacesetters - but concedes his side can ill afford to drop any more points.
"It's not totally over yet," he told German website sport1.de
"If we win all of our matches, then we've got a good chance.
"We've got to keep focusing on that and that's why we're taking things game by game.
"We're trying to concentrate fully on our next game against West Ham
We have a bit more time now that we're not in any other competition so we don't have to concentrate on anything else, other than the title."
The Germany defender hopes to be able to play his own part in prolonging Arsenal's title bid, admitting that being a substitute like he has been in five of the Gunners' last eight games is not something he wants to get used to.
"I've got to admit it is new to me," he said
"I've been around a long time now and this has not so often been the case, but I'm in good spirits, am fit and I have no pain.
"Of course I'm playing less, but I'm sticking at it
Maybe I'll get another chance
Things change quickly nowadays.
"You get ups and downs as a footballer and you've just got to remain professional, and I've always been that down the years.
"That's why I've survived for so long in this business
I listen closely to what the coach says and he knows that he can count on me, no matter what happens.
"I want to show him in every training session that I'm ready when needed
The team needs every player, whether I'm on the bench now or not - I don't just write it off.
"I always look ahead positively and that is the best way to get over the disappointment of not playing."
The 31-year-old World Cup winner has played 21 times for Arsenal in the Premier League this season, wearing the captain's armband in all but three of those appearances.
He still has a year left to run on his contract in London.
Source : PA
Source: PA