Roger Federer faces US Open nemesis in shape of Juan Martin del Potro

For Roger Federer it was one of those few occasions when a final got away from him.

In 2009, the now 19-time grand slam champion lost in five sets to Juan Martin del Potro – then only 20 – in the US Open final. The two players will meet again in the quarterfinals on Wednesday.

“The only time when he was really better, in my opinion, was the fifth set,” Federer told reporters as he looked back on his 3-6 7-6 (7-3) 4-6 7-6 (7-4) 6-2 defeat eight years ago.

On Monday, Federer cruised past Philipp Kohlschreiber 6-4 6-2 7-5 but his thoughts quickly turned to his match with Del Potro.

“It probably feels like one of those matches I would like to play over again,” added Federer, referring to the 2009 final.

“I feel like I would probably win it somehow because I should have been up maybe 2-0 or should have been up 2-1.

“It was a good match. A lot of back and forth. Crowd was really into it. Started in the day, finished in the night.

“I was not too disappointed I don’t think because I had a great run, you know, winning I think the French, Wimbledon and then the birth of my girls.”

Roger Federer is chasing his sixth US Open title.

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‘Del-Po! Del-Po!’

Del Potro’s success in 2009 also ended Federer’s five-year winning streak at the US Open, though the Argentine then suffered a series of injury problems – he has had to undergo four wrist surgeries.

On Monday, del Potro rolled back the years saving two match points before going on to defeat Dominic Thiem 1-6 2-6 6-1 7-6 (6-1) 6-4.

Juan Martin del Potro won his one and only grand slam title at the US Open.

The Argentine enjoyed huge support – chants of “Del-Po! Del-Po!” frequently rang out – as Del Potro, who has been struggling with flu symptoms, reached the US Open quarterfinals in New York for the fifth time in nine appearances.

“I played one of the epic matches of my career here in the US Open, which is my favorite tournament, in front of a great crowd,” said Del Potro speaking after his win on Monday.

“I was exhausted after the last point of the match. But I’m so glad to go through. I played a fantastic battle against one of the best players on the tour.

“I was thinking to retire in the middle of the second set because I couldn’t breathe, I couldn’t move well. Dominic was dominating the match so easily. But then when we started the third set, I broke his serve very quick, and then I won the set in 20 minutes.

“Then the story changed a lot. I started to see the crowd. I took all the energy from the fans. That’s what I did in the end, just keep fighting. I didn’t give up on any points from the third until the fifth set. I was ready to win the match in that moment.”

It's Maria Sharapova's 'least favorite place in the world"

But locker rooms are where tennis matches can be won and lost ...

Rafael Nadal of Spain poses in the locker room with the Coupe des Mousquetaires trophy at Roland Garros in 2014.

As well as a place of preparation for matches, locker rooms are also a perfect setting for posing for photos after winning trophies. Novak Djokovic is pictured holding the Butch Bucholz trophy after winning his fifth Miami Open title in 2015.

As the old saying goes: "By failing to prepare, you are preparing to fail." Jo-Wilfried Tsonga is pictured warming up at the Hamdan Sports Complex in Dubai in 2014.

Victoria Azarenka of Belarus is pictured at Crandon Park Tennis Center at the Miami Open. Azarenka, who also isn't competing at Roland Garros, recently hinted in a tweet this week she would play at Wimbledon later this year after intending to make her own comeback -- the Belarussian gave birth to son Leo in December and hasn't played since last year's French Open -- at a Wimbledon warmup tournament.

Another absentee from the French Open is Sharapova, who was denied a wild card by the tournament organizers.

Serena Williams will miss the 2017 French Open as she's on maternity leave. Last month her publicist confirmed Serena is expecting a child with her fiance, Reddit co-founder Alexis Ohanian, and is due to give birth in the fall.

"There is such a thing as locker room power," former British Davis Cup player Arvind Parmar told CNN Sport. Here Frenchman Tsonga of the Manila Mavericks gets ready in the locker room before his team's match against the Singapore Slammers during the Coca-Cola International Premier Tennis League at the Mall of Asia Arena in November 2014.

Stanislas Wawrinka of Switzerland is pictured posing with the Norman Brookes Challenge Cup in the players' dressing room after winning his men's final match against Nadal of Spain at the 2014 Australian Open at Melbourne Park.

Access is normally restricted to players and coaches only, though exceptions can be made. Real Madrid icons Cristiano Ronaldo (L) and Raul are pictured posing with Nadal during the Madrid Masters in May 2010.

Britain's Andy Murray heads back to the locker room after finishing a practice session at Wimbledon.

London's Queen's Club's dressing room decor has a more old school feel.

Success = champagne celebration in the dressing room. Djokovic is pictured celebrating after winning 2008 Australian Open final against Tsonga in 2008.

Switzerland's Roger Federer is filmed by a TV crew holding the Wimbledon trophy as he enters the dressing room after beating Andy Roddick of the US in the 2009 final. Federer has opted not to play at this year's French Open.

Photos: What goes on in tennis locker rooms?

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Looking ahead to Wednesday’s meeting with Federer, Del Potro said it was going to be an “interesting” match to play.

“I know how to play if I want to win, but always is a pleasure to play the greatest guy in history.”