MASON, Ohio — Despite the adage about “old dogs,” Roger Federer is still learning new tricks at 34.

The latest — a sudden rush forward nearly to the service line to return his opponent’s second serves — he has deployed bravely and brazenly against stellar opposition throughout his run at the Western & Southern Open in suburban Cincinnati, where he dispatched Andy Murray, 6-4, 7-6 (6), in a semifinal on Saturday afternoon.

The tactic would seemingly be more at place in an outdated video game than at the elite levels of professional tennis, and Federer, who will be seeking his seventh title at the tournament when he faces Novak Djokovic on Sunday, said he started using the strategy just for laughs.

“I did it in practice more as a joke, and I tried it again and again and again, and it just seems like it’s not that hard — for me — to do,” Federer said. “Plus, it makes you play very committed. Up there, there is no room for not being committed; otherwise you’ll lose the point every single time. It’s very much all about timing and reaction.”

Federer added that although the maneuver could break a player’s rhythm or play with an opponent’s mind, “I’ve still got to understand when I can do it, when I should and shouldn’t do it.”