New York: Call it sneaky, call it 'Sabre,' call it the new weapon that could just fire Roger Federer to his sixth US Open and 18th Grand Slam title.
The world number two has developed a new attacking ploy which is bamboozling opponents and providing the 34-year-old Swiss with yet another dimension to his already impressive game.
It involves chipping and charging on a second serve, starting from a position inside the baseline and ending with a quick sprint to the service box.
"We sort of came up with the name, you know, 'Sneak Attack By Roger,' 'Sabre.' Call it 'Fed Attack,' call it whatever you want, but I thought it was kind of funny," said Federer.
Although he had mixed success with it on Saturday, the world number two still had plenty of other tricks up his sleeve to make the last 16 with a 6-3, 6-4, 6-4 victory over Philipp Kohlschreiber.
It was his 10th victory in 10 meetings against the German player as he reached the second week in New York for the 15th successive year.
Federer arrived in New York having rebounded from his Wimbledon final defeat to Novak Djokovic with a seventh Cincinnati Masters title.
It was at the Midwest venue where Federer developed his new tactic, almost by accident when he was practicing with French player Benoit Paire.
Both men were just looking for a gentle workout with Federer still dazed by jet-lag and Paire laid low with an ear infection.
"I was very tired and he was tired, and at the end we said, 'Well, let's still play some games just because it feels like it's the right thing to do,'" explained Federer.
"I was going to stop already, but (coach) Severin (Luthi) said, play a few games get used to the conditions.
"I said, Whatever. Let's play some games. And, yeah, at the end we were just kidding around almost, and that's when I said, OK, I'm going to chip and charge and just keep the points short.
"That's when I started to run in and hit returns. I hit a couple for a winner. They were like ridiculous. He laughed. I laughed. Severin laughed."
Federer said he never imagined using it in match play and that it was Luthi's persuasion that kept the tactic on the boil.
"Severin said, 'Well, what about using it in a match?' I was like, 'Really?' So he pushed me to keep using it and not shy away from using it on big moments, and not just because you don't know how you look with a full stadium.
"He was actually the one who pushed me to it. And because we were always talking about that tactic, as well.
"Moving forward it's an option. Clearly I'm very happy it worked so well in Cincy."
Federer undecided about SABR's use against Isner:
Roger Federer though might not be so keen to try out his old-dog-new-trick, rush-the-net "SABR" - "sneak attack by Roger" - return strategy against his next opponent at the U.S. Open.
"I don't think so," Federer said. "I can always try. But it's probably not the right guy to do it against."
Probably not.
That's because the second-seeded Federer will have to deal with 6-foot-10 American John Isner and his massive serve in the fourth round.
"The idea is not to use it very much against a player like that," Federer said about his innovative and risky approach to attacking second serves, racing forward as the ball arrives to pluck it off the ground with what amounts to a half-volley.
"I have done pretty well over the years against big servers, so, I mean, clearly I will think about it. But I don't think that's going to be the turning point of the match, to be quite honest. I need to make sure I protect my own serve first."
