The Czech Republic international secured a transfer to Chelsea’s London rivals last week after falling down the pecking order at Stamford Bridge following Thibaut Courtois’ return from his loan spell at Atletico Madrid.
Cech is likely to be Arsenal’s number one choice between the posts next season as Arsene Wenger looks to guide the north London side to a genuine Premier League title challenge.
However, after spending 11 years playing for Chelsea, former Arsenal shot-stopper Lehmann feels that Cech will need to put his ties to the west London club behind him right away.
Lehmann told the Sun: “It’s not easy to suddenly go from Chelsea, where he has spent almost his whole career winning many trophies, to the other side of the capital with 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. But, as a professional, he needs to get over it and needs to know Arsenal want him to win things again for them.
“Yet, let me tell you, that is not an easy thing to get over psychologically. It can take a few weeks, even a few months.”
Cech has more than 114 caps for the Czech Republic and joined Chelsea from Rennes back in 2004.
He has already passed his medical with the Gunners and will join up with his new team-mates shortly to begin preparations for the 2015-16 season.
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