The former Werder Bremen man said focus will be vital, and how they cannot afford any more slip ups, as reported by talkSPORT:
"It's not totally over yet. 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."
Arsenal have returned to winning ways in recent weeks, with back-to-back victories over Everton and Watford, but they have failed to make a dent into Leicester's lead.
With his side being knocked out of the Champions League and the FA Cup in recent weeks, Mertesacker claims they are re-invigorated, now that they only have one competition to focus on:
"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."
Mertesacker, 31, has played 21 Premier League games for his club this term, and has received criticism from pundits and fans alike for a string of poor performances, accentuated by his lack of pace.
He was ruthlessly exposed in Arsenal's home game against Chelsea where he saw red for a reckless lunge on Diego Costa.
Since then he has only appeared in three of the Gunner's eight league games - a statistic that is indicative of manager Arsène Wenger's seemingly diminished trust in the World Cup winning centre-back.
The Frenchman has opted for Gabriel Paulista's pace over Mertesacker's experience in recent weeks, and with back-to-back clean sheets, that will be unlikely to change when they visit Upton Park on Saturday.