SOMETHING has to give when Novak Djokovic takes on Roger Federer for the US Open title today as the best attacking player in the sport faces the man who has made defence into a new art.

The world’s top two meet for the 42nd time, with Federer nudging in front at 21-20 after his win in the final of Cincinnati last month.

Djokovic, in his fourth straight Grand Slam final, will be going for slam win No 10 while Federer will be trying to make it to 18.

Having lost to Djokovic on grass in the Wimbledon final, Federer is the slight underdog, chasing his first Grand Slam title since 2012, at the age of 34.

But it’s the dynamic between the two which is likely to make this so special. A couple of weeks before Djokovic reached his first Grand Slam final, at the US Open in 2007, Federer made it known, quietly, that he didn’t rate him that highly. The Swiss won that final in straight sets but soon began to realise the Serb was a real danger to his dominance.

What has happened in the interim has not only pushed Djokovic into the conversation for best player of all time; it has also forced Federer to improve again.

His new-style return – nicknamed SABR for Sneak Attack By Roger – has been drawing all the headlines this summer, the sight of Federer taking the serve on the half-volley and coming into the net putting the wind up most of his opponents.

It’s been a successful tactic, not because Federer was not capable of anything he put his mind to, but because in these days of extra power and spin, controlling the returns is far from easy. But what that particular shot, dreamed up by Federer and his coach Severin Luthi towards the end of a training session in Cincinnati, has cleared his mind, allowing him to play on instinct, something that served him so well over the years.

Federer, who crushed Stan Wawrinka in the semi-finals, has used it to stunning effect and having done it against Djokovic, at times, there is no reason he won’t try it again today.

“If it makes sense, I’ll use it in the finals,” he said. “I used it to great effect against him in the tough situation, as it was at 4-1 in the breaker in Cincy. We will see if the occasion presents itself. It’s got to be the right point, right frame of mind, the right place to do it. I hope I’ll have the opportunity to do it.”

Novak doesn’t like it either, as he let slip yesterday after demolishing an injured Marin Cilic, the defending champion, in his semi-final.

“He tried that in Cincinnati and it worked a couple of times,” Djokovic said.

“It’s an exciting shot for him. For the player opposite side of the net, not so much.

“So I have nothing else to say about that.”

Djokovic has won just one US Open final from five, a record he is desperate to improve. “Win or lose on Sunday, it still has been so far a great year, best year alongside of 2011,” he said. “But I’m only thinking about winning and winning that US Open trophy. It’s why I’m here, and I will try to make it.”

Federer said neither he nor Djokovic need to deviate much from their natural game, a fact highlighted by their two semi-finals in New York when Djokovic beat Federer, saving match point on both occasions.

“I think it’s just a straight shootout, and I think that’s the cool thing about our rivalry, it’s very athletic,” he said. “We both can handle whatever we present to one another and our matches, it’s very even. That’s it, I think. I don’t need to add more here.”