The former Gunners keeper does, however, believe that question marks linger regarding Arsene Wenger's side and their title credentials.
The vastly-experienced shot-stopper left Chelsea for a move across London this summer after finding himself on the bench with the Blues following the emergence of Thibaut Courtois as Jose Mourinho's number one.
It was widely regarded as a clever move from Arsene Wenger to secure the veteran Czech international, with the goalkeeping positing having been one of particular weakness for his side for a number of years.
And Lehman is among those who think Arsenal completed shrewd business in securing the services of a proven performer, claiming that Cech doesn’t have any weaknesses.
“Petr is one of the greatest goalkeepers ever,” he told ESPN.
“I think that was a really good purchase by Arsenal, you can’t perform in every game but Petr has the ability to tick every box in terms of goalkeeping, he doesn’t really have any weaknesses.”
Same doubts still linger about Arsenal
The Gunners were picked by many as potential Premier League champions this season, but have had a relatively difficult start to the campaign.
They opened their title bid with a shock defeat to West Ham United, but have since recovered to beat Crystal Palace, Stoke City and Newcastle United and draw with Liverpool.
However, they have failed to impress and a midweek loss to Dinamo Zagreb in the Champions League has got everyone questing their credentials again, and Lehman says the same doubts remain that have followed the club around for a number of years now.
“I hope so, that Arsenal would win the Premier League this year,” he added.
“Watching the game where they’ve lost against Dinamo Zagreb, again there’s always the same doubt.”