Former Arsenal goalkeeper Jens Lehmann believes Petr Cech will bring a winning mentality to his new club but warned it will be difficult for him to emotionally adapt after spending so long with London rivals Chelsea.
Cech, 33, joined Arsenal last week to bring to an end an 11-year spell at Chelsea in which he won four Premier League titles, four FA Cups, three League Cups, the Champions League and Europa League.
Lehmann, who played for Arsenal between 2003 and 2008 and then returned briefly in 2011, hopes Cech can help the club win a first league title since 2004.
"I cannot believe it has been 11 years now since the club won the Premier League," he said in The Sun.
"We had another two chances to win it when I was still playing there, but they then got rid of all the older guys along with that dressing-room experience and winning mentality and, since then, they've not been able to get back into it on a consistent basis.
"Yet with someone in there like Petr, with Per Mertesacker now as captain, they can re-establish this winning attitude and mentality. That is why I think getting Petr was a great move by Arsene Wenger. Not only is he among the best keepers ever, he's a winner."
He added: "Petr has maybe five fantastic years still ahead of him, as long as he doesn't get injured, so for me this is the best deal Arsenal could possibly have done this summer."
However, Lehmann said Cech may find it tough initially.
Lehmann made his name over a 10-year spell at Schalke before moving to arch-rivals Borussia Dortmund in 1999 after a brief stint with AC Milan, and he faced initial hostility from BVB fans, who at one stage raised a banner reading: "Once an enemy, always an enemy."
Lehmann said: "It's not easy to suddenly go from Chelsea, where he has been for almost his whole career winning many trophies, to the other side of the capital for a rival.
"Before you can have it in your heart to win titles again, you have to get rid of the love you had before.
"At Chelsea, for Petr, it was his passion and he showed great commitment -- and was probably in love with them -- but, as a professional, he must get over it and needs to know that Arsenal want him to win things again for them."
Lehmann, who won the UEFA Cup with Schalke in 1997 and Bundesliga title with Dortmund in 2002, added: "Let me tell you, that is not an easy thing to get over psychologically ... it can take a few weeks, even a few months."
The German said Cech should adapt quickly on the playing side, though, and that he communicates better with his teammates than current Chelsea No. 1 Thibaut Courtois.
"I don't think it'll take him time to get used to playing with a new set of defenders," he said. "Petr had one big advantage over Thibaut. Although he, too, is a fantastic keeper, he does not interact much with his teammates -- whereas Petr does.
"Also he has a faster brain than most people, and it's so much easier for someone with his vast experience to react to certain things than a much younger keeper.
"After all those years at Chelsea, he'll have seen and been in many situations thousands of times before. That is going to be beneficial to not only the defenders but the whole team."