LONDON -- Arsene Wenger says he isn't afraid to get tough with Mesut Ozil, but has defended the German's much-criticised performance against Tottenham.

Ozil was again singled out by pundits following Arsenal's performance in the 2-0 defeat at White Hart Lane on Sunday, with some questioning his commitment and attitude amid a long standoff concerning a contract negotiation.

It has also led some to question whether Wenger is tough enough on the playmaker, especially in contrast to Jose Mourinho, whose Manchester United side is up next for the Gunners on Sunday.

Ozil writes in his new autobiography that Mourinho's way of motivating him at Real Madrid sometimes included heated arguments in the dressing room, and that the Portuguese manager even called him "a coward" for not going into tackles.

Wenger uses a much less confrontational style with his players -- but insisted that he's had a few choice words to say to Ozil at times as well.

"Yes he needs [tough love]," Wenger admitted. "We had some good conversations with him as well, you know. But he has not necessarily had time to write the book so you don't know about it. I don't tell you what I tell them."

Ozil showed great form in the first half of the season, but his productivity has dropped off dramatically since Christmas. However, Wenger insisted that the performance against Tottenham was in part due to fatigue following the FA Cup semifinal win over Manchester City and league victory over Leicester.

"To just criticise Mesut Ozil's performance does not reflect exactly what happened on the pitch," he said. "Overall I believe recently he has put a lot of effort in. He was a bit, like the rest of the team, not physically at his best. I felt that we gave a lot on Sunday [against City], Wednesday and had not completely recovered for the game.

Mesut Ozil has come under fire from fans for some of his recent performances. John Patrick Fletcher/Action Plus via Getty Images

"And he was one of them as well. Overall the big players get more criticised than the others. Secondly his style is more fluid, less aggressive but it doesn't mean you want it less than others."

Ozil's up-and-down form has been a source of frustration to fans, who have seen him mix world-class performances with disappearing acts too often this season. But Wenger said even superstars can't be at their peak every game.

"At the end of the day you want all your players to be at their best in every single game so when they don't achieve that of course you are frustrated," he said. "But we've all played football, we know we are only human beings and you have to accept the ups and downs."

Ozil and fellow star Alexis Sanchez have yet to agree contract extensions, with talks now on hold until the summer. With both demanding wages north of £250,000 per week, some fans are now starting to question whether the duo is actually worth that money.

Wenger has repeatedly said he expects both players to eventually sign new deals, but insisted that the club has to take other players into consideration before handing mega deals to the star duo. Alex Oxlade-Chamberlain, Aaron Ramsey and Jack Wilshere are among other Arsenal players who will also need new deals this summer.

"You know me for a long time, before we spend big money we analyse all the aspects of commitments because we have not only Mesut Ozil and Sanchez to extend," he said. "We have many other players to extend and you have to make sure you have the resources available to extend the other players that you think are needed to be successful in the future."

If Ozil doesn't sign a new deal, he shouldn't have any shortage of suitors come in for him, despite his inconsistent form this season.

But when asked if Arsenal have received any offers for him, Wenger insisted: "No. Not officially."