Lesnar is signed with the WWE through Wrestlemania in 2015 and he has a specific number of appearances written into his contract. This will be a busy first half of the year for Lesnar. He is scheduled for the "Royal Rumble" pay-per-view, "Elimination Chamber" pay-per-view, and "Wrestlemania 30."
The Big Show match was set up when Brock Lesnar broke Mark Henry's arm and Big Show came out to prove that Lesnar wasn't the biggest man in the locker room. He then manhandled The Beast and threw him across the ring.
From the recent WWE rumors, Lesnar will battle Big Show at the "Royal Rumble" and then enter the "Elimination Chamber" in the cage for the big specialty match. That will lead to the "Wrestlemania 30" match, which is still up in the air right now.
The biggest rumors indicate that Lesnar will battle The Undertaker at "Wrestlemania 30," but with Undertaker not as healthy as he used to be, and Lesnar preferring a more physical style of match, it might not be the best idea. Whoever Lesnar fights, it will have to be a big match and CM Punk seems to be the next best choice.