In the spirit of Wimbledon, we’ve got a link here from Mashable to the 20 most shared ads featuring tennis players. So what seems to be working? Roger Federer (he’s in seven), flashing some skill (and a little skin, in the case of Rafael Nadal), and humor. We’ve got one here that pulls all that together into one two-minute package. This Head commercial stars world number two, the gluten-free Novak Djokovic.