Partial Source: The Wrestling Observer
There were always plans for Brock Lesnar to make his return before the Royal Rumble pay-per-view, but they weren't sure if he would have a singles match or just be used in the Rumble match itself.
There were discussions about having Brock face The Big Show at the event in Pittsburgh, Pennsylvania, but it's unknown if those plans are still in place.
As noted Monday night on RAW, Lesnar will face the winner of the Randy Orton vs. John Cena WWE World Heavyweight Title match at the Royal Rumble pay-per-view.
More details about Brock's Rumble appearance will likely be revealed next week on RAW.