Source: The Wrestling Observer Newsletter

The original plan for The Big Show at the Royal Rumble was to face Brock Lesnar with Show as a main event player by the time the pay-per-view arrived. The plan was discussed before WWE unified the titles when Show was feuding with the Authority. He was expected to get big victories over Randy Orton and Triple H, without winning the title, to end up looking strong for a match with Brock Lesnar at the Rumble. Lesnar would then have defeared Show to look strong for his match with The Undertaker (or someone else if they do 'Taker vs. Daniel Bryan) at WrestleMania 30.

It's unknown if this is still the plan moving forward now that Show has been phased out of a program with Orton/The Authority after losing at Survivor Series, but it was the plan as of a few months ago.