Lehmann stated that Özil has the talent to make the difference in big games but that he has not shown it yet wearing an Arsenal shirt.
The former Germany international keeper believes Özil has a lot more to give Arsenal. Lehman underlined the Özil can help Arsenal win domestic and European titles in the future.
“Arsenal bought him to win championships nationally and internationally,” Lehmann told Perform.
“That should be his goal. He can’t do that on his own but he should be the one making the difference in big games. He’s got the potential but has to show it.”
Arsenal have won eight consecutive Premier League games and the Gunners have won 13 out of the last 15 matches in which Özil has played.
Özil has directly contributed to seven goals in his last nine league games for the North London based club.
The Gunners take on Championship side Reading in an FA Cup semifinal at Wembley on Saturday.