Cech kept a sixth clean sheet in 11 Barclays Premier League games as Arsenal swept aside Swansea 3-0 at the Liberty Stadium to keep pace with league leaders Manchester City.
The 33-year-old has made a smooth transition to life at Arsenal after 11 trophy-filled years at Chelsea, while his former club are suffering a disastrous season with Jose Mourinho's position coming under increasing scrutiny.
"You know that if they get a really clear chance Petr can do something about it," Mertesacker said after Cech had thwarted Swansea b efore Arsenal took command in south Wales
"He's always someone who can save your day
That gives everyone a big lift, not only the back four.
"The way he is commanding and vocal makes him vital
He is one of our leaders and he deserves it.
"He has played at a high level and he is still very hungry and, no matter how successful he was at Chelsea, I think he gives our team that hunger we maybe need.
"He is an experienced player that everyone looks up to and he's important for our structure as well."
Arsenal secured a fifth straight league win through second half goals from Olivier Giroud - the 2,000th of manager Arsene Wenger's 19-year reign - Laurent Koscielny and Joel Campbell's first for the club.
Withstanding Swansea's impressive opening provided further evidence that Arsenal are ready to mount a title challenge this season, and German veteran Mertesacker feels the Gunners are stronger for their past disappointments.
"We haven't proved anything yet but what we have learned is to take it game by game," Mertesacker said.
"The last couple of years we have lost a few games here and there, especially away from home.
"But we take it really seriously because we can see there is not that much difference between the top and us.
"Last season I think it was 15 points at this stage and now it's completely different.
"It gives you a reason to be as efficient as we are at the minute."
Arsenal head to Germany next with a crunch Champions League game at Bayern Munich on Wednesday night.
Bundesliga leaders Bayern suffered their only defeat of the season at the Emirates Stadium two weeks ago, and Arsenal need another positive result in Bavaria after shock opening group defeats to Dinamo Zagreb and Olympiacos.
"They will be angry," Mertesacker said.
"We are the first team that really challenged them and beat them at the end, so they will try to show they are better than us.
"They played on Friday to get well prepared for the midweek - the Germans are clever!
"But we improved our position in the last game against Munich and we need to get something out of this game
"That puts pressure on us to perform and we need to defend even better."
Source : PA
Source: PA