That is the opinion of former Arsenal and England goalkeeper David Seaman.
Leno joined the Gunners from Bayer Leverkusen for £19million earlier this summer.
His arrival has cast doubt over the future of Petr Cech, David Ospina and Emiliano Martinez at the Emirates.
The 26-year-old German already has seven seasons of regular Bundesliga football behind him, but Seaman does not think he is ready for the Premier League.
Cech was the No 1 at the Emirates under Arsene Wenger last season and Seaman believes the former Chelsea man should remain as the first choice for the upcoming campaign.
“The Cech situation puzzles me a bit, because we still don’t know who is going to number one at Arsenal,” Seaman told talkSPORT.
“Would I start the season with Cech? I think so.
“It depends what’s happening in training. Emery will be watching in training and in the friendly games to see who is performing the best.
“I think it would be a big gamble to put Bernd Leno in straight away, because I can’t image Petr Cech wanting to hang around as a number two anywhere at this stage of his career.
“So Emery has to be a bit a little bit careful with his choice.
“But I would still go with Petr Cech.”