Sergio Busquets in the Champions League final, the biggest game in club soccer, against Manchester United, putting in a nearly perfect display of how to be a holding midfielder.
Busquets has, in 3 years gone from youth player to absolutely vital player for Barcelona and Spain, winning 3 Spanish Leagues, 2 Champions Leagues, and a World Cup.
He is the least acclaimed of the Barca midfielders, although he is finally getting the respect he deserves in some circles, but he is just as important in my view. He usually has the second most passes after Xavi, who may be the best passer ever, he breaks up opposition attacks, he can fill in as a defender, either at the start of the game as a center back in a back 4 or any of the positions in a back 3, or drop into the back line during the game to switch from a back 4 to a back 3. Also he is one of the 3 players for Barca that are genuine threats in the air on corner kicks and other set pieces.
This season Barcelona have revolutionized the entire idea of a defense; partly through injury and partly through innovation. Often times Barca will play with no recognized center backs at all, instead starting midfielders there, realizing that since they will have the ball most of the game, it is more important for their defenders to be good passers than just destroyers. The key man in all of this is Busquets.