Rangers could extend their lead at the top of the Championship to eight points but face a tough task against Brian McDermott's Royals, who are unbeaten in their last six matches.
"Reading are a good side," said Warnock.
"Brian has done a great job there and they are absolutely flying at the moment.
"They don't come much more difficult than Reading away. There are no easy games in this division, though.
"On Sunday night, when all the other teams have played, if we're still sitting a few points clear, we'll be really delighted."
Source: PA
Source: PA