Mikel John Obi may be exactly the same age as David Luiz (both born April 22, 1987), but the Nigerian international is one of Chelsea's elder statesmen. He's the second longest-serving active player in the squad and is tied for 15th on the all-time appearances list with Charlie Cooke. (At just 29 years of age, Mikel still has a chance to reach lofty heights on the all-time appearances list, provided he signs a new contract this year.)
While he's been away from Chelsea for most of the summer on Olympics duty with Nigeria (and winning bronze), Mikel's still got the pulse of the squad and using his new-found love of Twitter, welcomed Sideshow Dave back to Chelsea, and reminded him to play nice with Diego Costa.
Just as he had clashed a bit with John Terry before joining Chelsea, Diego and David Luiz had their fun while facing each other in various combinations of the colors of Atletico Madrid, Chelsea, and PSG. Here's just a small sample.
But now they're teammates, after just missing each other in the 2014 transfer window, so we no longer have to worry about who will get whom sent off. With both in the fold, we're in for some (fun?) shenanigans.