The insane stats behind World No.78's upset of Roger Federer

World No.78 Grigor Dimitrov has brushed aside a lengthy list of concerning statistics to complete an against-the-odds US Open victory for the ages in a quarter-final boilover against 20-time grand slam champion Roger Federer.

The Bulgarian launched a dramatic fightback to defeat the Swiss third seed 3-6, 6-4, 3-6, 6-4, 6-2 at Arthur Ashe Stadium to set up a semi-final showdown with Russian fifth seed Daniil Medvedev.

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The former World No.3 - now 78 in the world standings - went into the clash against Federer as a massive underdog.

Dimitrov had never once beaten the Swiss maestro in their seven previous attempts, making the Bulgarian's victory even more astonishing.

The 28-year-old's career appeared to be at the crossroads after he crashed to a straight sets defeat to a qualifier outside the top 400 in Atlanta less than two months ago.

After asking for a wildcard to the tournament, Dimitrov's career hit a new low after he was unceremoniously dumped out 6-4 7-5 against World No.405 Kevin King.

In fact, Dimitrov's build-up to the US Open had been anything but positive, the Bulgarian with only one win in eight matches before he tournament got underway in New York.

Dimitrov's world ranking was the lowest it's been since June 2012, when he was the World No.87.

His last semi-finals appearance in any tournament came almost 18 months ago when the Bulgarian lost to Rafael Nadal at Monte Carlo.

Yet despite all the evidence pointing to an inevitable Federer victory on Athur Ashe Stadium on Wednesday, Dimitrov did the unthinkable, to leave the tennis world in shock.

The extraordinary victory saw Dimitrov defy another incredible statistic as he became the lowest ranked player to reach the semis-finals of the US Open in 28 years.

"I'm just happy," Dimitrov said. "The only thing I was telling myself was to stay in the match. Physically I was feeling pretty good. I was hitting some shots against him that were hard to hit."

Dimitrov’s first US Open semi-final sees him match the deepest Slam runs of his career from Wimbledon in 2014 and the 2017 Australian Open.

Not since 174th-ranked Jimmy Connors reached the 1991 quarter-finals had New York seen so lowly a figure on the ATP ratings list reach the last four.

Dimitrov is also the lowest-ranked Slam semi-finalist since 94th-rated Rainer Schuettler of Germany at Wimbledon in 2008.

His next opponent Medvedev defeated three-time Grand Slam champion Stan Wawrinka 7-6 (8/6), 6-3, 3-6, 6-1 to reach his first major semi-final, shaking off a sore left quadriceps that made him contemplate quitting the match. Now he gets two days of rest.

Federer, a five-time US Open champion who has not won at Flushing Meadows since 2008, breezed through the first set in 29 minutes and appeared to have withstood the danger until Dimitrov opened the fourth set with a break.

Federer was denied on five break points in the 10th game of the fourth set and Dimitrov held to force a fifth set.

"I was trying to stay in that game and make him stay on the court as much as possible. After that he started slowing down a little bit," Dimitrov said.

"It's a best of five sets. Anything can happen."

Federer went off the court for a private medical timeout to treat his upper back near his neck.

"This is Grigor's moment, not my body's moment," Federer said.

Dimitrov broke Federer twice on the way to a 4-0 lead in the final set and the 38-year-old Swiss star had no effective reply, foiled by 61 unforced errors in falling after three hours and 12 minutes.

"It's OK. It's how it goes," Federer said. "I tried my best. I fought with what I had and that's it."

Federer would have become the oldest Slam semi-finalist since Jimmy Connors at age 39 at the 1991 US Open.

With agencies