In case anyone was curious, this is how you execute a counterattack.
Notice how Danny Welbeck (the guy who sends Nani clear with his pass) waits until the last possible second to play the ball forward. This is the sort of timing that only comes through hours spent on the training ground (and is also helped by an excellent decision by the linesman, who rules Nani onside). The finish itself isn't particularly great, as Nani opts for power over placement or subtlety and drives the ball between Victor Valdes' legs. And then, of course, there's the back flip celebration, which really never gets old, no matter who does it.
Nani has had an up-and-down Manchester United career since 2007, when he arrived from Sporting Lisbon, often being compared (somewhat unfairly) to his fellow countryman and former teammate Christiano Ronaldo. Though he's often been the subject of Sir Alex Ferguson's frustrations, there's no doubt he has tremendous talent and this is just one more piece of evidence for it.