Cape Town - Spain's 14-time grand slam winner Rafael Nadal believes that newly-crowned US Open champion Stanislas Wawrinka is capable of winning more slams.The Swiss world No 3, who defeated world No 1 Novak Djokovic in the US Open final on Sunday, has won three grand slam titles, Australian, French and US Opens and Nadal has predicted that Wawrinka will add to that tally.In an interview ahead of the weekend's Davis Cup tie against India, Nadal told reporters that when Wawrinka was on form he was cable of beating anyone."Stan is a player that over the last couple of years has been playing great tennis," said Nadal. "When he is playing well he is able to play very well against all opponents."Though Spain is expected to comfortably defeat India this weekend, Nadal said they respected their opponents and would take nothing for granted. "We lost a couple of confrontations that we believed we were the favourites (for) and we were in a good position to win, so maximum respect for all opponents, for India."