Ramsey ruled out of Tottenham showdown
Wales midfielder Ramsey has not played for Wenger's men since the 3-1 win at West Ham back in December because of a thigh problem.
The 23-year-old had targeted a return against Arsenal's north London neighbours, but Wenger revealed on Thursday that Ramsey's prospective comeback has been pushed back.
"We have had to defer his comeback to full training a little so he is not available," Wenger told Arsenal's official website.
"He is having difficulties in the final stages of his rehab. It looks to be short-term."
Mesut Ozil picked up a hamstring injury as Arsenal were knocked out of the UEFA Champions League by holders Bayern Munich in midweek.
The German will definitely miss Sunday's trip to White Hart Lane, but Wenger still does not know the full extent of the injury.
"He (Ozil) is out. I don’t know for how long but it is a hamstring injury. There are scans going on," Wenger added.
However, Kim Kallstrom, who joined on loan from Spartak Moscow in January but has yet to make his Arsenal debut because of a back problem, could be fit to fill the void left by Ozil.
In a further boost to Wenger, left-backs Kieran Gibbs and Nacho Monreal may also be available to face Tottenham.
"Kallstrom joins the normal training group today (Thursday) and (Yaya) Sanogo too," Wenger explained.
"I will have to decide if Kallstrom is OK to be in the squad on Sunday. I will see how he looks, it is not impossible.
"Kieran Gibbs has a test tomorrow (Friday) but I am hopeful that Nacho Monreal will be fit. They both have a good chance."