Federer's sneak attack disrespectful to opponents: Boris Becker

Legendary tennis player Boris Becker has slammed 17-time Grand Slam winner Roger Federer, describing the latter's new chip-and-charge return tactic as 'almost disrespectful' to opponents.

Becker, now coach of Serbian star Novak Djokovic, spoke about Federer's recent strategy of standing right up to receive serve and then running in, after hitting it almost on the half volley.

The Swiss star used the tactic, which involves charging towards the net as his opponent serves, during a dominant 6-3, 6-3, 6-1 scamper into the semi-finals of the US Open against Frenchman Richard Gasquet on Wednesday night.

The German legend said that in his day, players would have smacked the ball straight at Federer's body to try and warn him off a move known as the SABR -- Sneak Attack By Roger.

"It's almost disrespecting the other guy's serve. Everybody talks about that's his new strategy -- he comes in. It's within the rules.

"If he would have played a (John) McEnroe, (Jimmy) Connors, (Ivan) Lendl or even me, we would have said, "Roger, in all honesty I like you very much, but I'll go straight at you. In my generation guys would not have accepted as it is now," Becker was quoted as saying by Skysports on Thursday.

Federer will next face compatriot Stan Wawrinka in the men's singles semi-finals of the US Open.