Eight-time Wimbledon champion Roger Federer and two-time winner Petra Kvitova may be entering this edition of the tournament, beginning Monday, as favourites but there are at least two more names who can upset the applecart. And that's not necessarily based on skill and physical prowess, but mental ability.

Rafael Nadal and Serena Williams will be coming into SW12 with a baggage of mental demons of their own. Injuries somehow keep creeping into two-time Wimbledon champ Nadal's life, while Serena is returning to London after becoming a mother last September. Federer too doesn't particularly have age on his side, considering he's just around a month shy of his 37th birthday.