What do you guys think? He doesn't do it regularly like Nadal, so it's a bit curious.
http://www.youtube.com/watch?v=dFSOk_THvDQ
http://www.youtube.com/watch?v=YtzI0tFwu4U
http://www.youtube.com/watch?v=dFSOk_THvDQ
http://www.youtube.com/watch?v=YtzI0tFwu4U