-- NEW YORK -- Top-ranked Novak Djokovic broke Andy Murray physically and mentally in his last match. Second-seeded Roger Federer refused to crack while roaring back from two sets down in his five-set thriller Thursday against Gael Monfils. "Mentally," Federer said afterward, "I'm always going to be there."
But the greatest danger posed by the two less-heralded players Djokovic and Federer will face in their back-to-back US Open semifinals on Saturday is that both Kei Nishikori of Japan and Marin Cilic of Croatia got this deep in the tournament in similar ways. They've all shrugged off some broiling conditions, grinding fatigue and matches that dragged deep into the night.
Neither Nishikori nor Cilic can touch Djokovic's and Federer's combined 24 Slam titles. Neither underdog has ever appeared in even one major final. But like Djokovic and Federer, Nishikori and Cilic credit superstar coaches for the changes in their games that have helped them get this far.
It seems there's some benefit of The Greats teaching greatness, no matter where you fall on the tennis food chain.
Djokovic's latest coach is Boris Becker, a man who knew something about playing in an era populated by legends on par with the Federer-Nadal stranglehold on the sport that the top-ranked Djokovic has successful bucked.
Djokovic hasn't played Nishikori, who enjoyed a short stay in the Top 10 rankings a few years ago, since 2011. But he has noticed the career renaissance that Nishikori credits partly to getting healthy and partly to his coach Michael Chang, who, like Nishikori, was also small in stature. At 17, Chang slayed then-No. 1 Ivan Lendl in 1989 in one of great French Open matches ever -- a match in which Chang won while serving underhand after cramps began wracking his body. Then he went on to win the title.
"He's helping me mentally -- he's very strong mental[ly]," said Nishikori, who had to rebound from a 4-hour-19-minute night match against Milos Raonic that didn't end until 2:26 a.m. to beat Australian Open champ Stan Wawrinka in another five-set war the next afternoon that lasted 4 hours and 15 minutes.
Nishikori didn't get to sleep until 6 a.m. the day of his Wawrinka match. He was so weary afterward, he didn't even bother to raise his arms in victory as he walked to the net to shake his opponent's hand.
Djokovic has a 1-1 career record against the 10th-seeded Nishikori. But he says a lot has changed in the three years since they last met.
"He's been playing the best tennis of his life the last 12 months," Djokovic explained. "He started working with Michael Chang and he changed a few things in his game. He serves very efficiently. Obviously he's very, very fast -- maybe one of the fastest on the tour. Great backhand, great forehand. All-around player."
Cilic has a comeback story too. He was watching the US Open from his sofa last summer. And he remains unhappy about the drug suspension that tennis authorities gave him and later rescinded, saying they now accepted his explanation that he'd ingested only an over-the-counter glucose pill.
"It was already four months past ... that was difficult to understand," says Cilic. "You are all the time on the tour from one day to another, and [then] you are not anymore. It was just very difficult even to deal with that."
But Cilic, who is 25, now says there was a bright side to his forced hiatus: He re-worked and added to his game with help from former Wimbledon champ Goran Ivanisevic, his childhood idol in Croatia, who is also tall and lanky and featured a blistering serve. Together, they buckled down and worked day after day though they had no idea when Cilic would get to play again.
His match against Federer will mark his first Slam semifinal since he advanced that far at the Australian Open in 2010. But here's the difference.
"It's worth more now," Cilic said.
Federer was expansive after surviving his two fourth-set match points against Monfils about how his work with Stefan Edberg is paying off after someone pointed out one throwback stat that leaped off the page: Federer went to the net 74 times against the Frenchman, and won 53 of those points. Though serve and volley tennis was a feature of Edberg's game, Federer acknowledged it just isn't done much these days because the game and courts have sped up.
But then Federer went into a fascinating explanation about why the tactics made sense against Monfils -- and why they very well may work against Cilic's game too.
According to Federer, against players who "defend really well and make you play that one extra approach shot" he wants to be the aggressor and take control of the point "rather than the other guy on defense going for it big and killing the point.
"I know that Cilic is going to stay on the baseline and dictate play as much as he can," Federer added. "Otherwise, he's quite similar to Gael."
Federer hasn't won a US Open title since 2008 after winning five straight.
Though Federer is 5-0 against Cilic, he hinted that may not matter much come Saturday.
When told Cilic has said he's playing the best tennis of his career, Federer nodded and said: "I agree."