This was set to be a fascinating contest as Novak Djokovic, regarded by many as tennis’ best returner went up against Opelka, who possesses one of the game’s biggest serves.

It would be the serve that won on this occasion, as Opelka claimed a 7-6, 6-3, victory to move into the semi-finals.

Novak Djokovic suffers shock defeat to Reilly Opelka at the Brisbane International

Opelka also became the first American man to defeat Djokovic since Sam Querrey claimed victory against the former World number one at the 2016 Wimbledon Championships.

The 27-year-old, ranked 23 in the world was flawless on serve, registering 16 aces. He also won 77% of his first serve points and just lost two points behind his second serve.

His straight set win means Opelka is the lowest ranked player Djokovic has lost to since he retired from his match against Filip Krajinovic in 2010.

His compatriot was ranked number 319 when Djokovic could no longer continue their contest in Belgrade after losing the first set.

In terms of completed matches, this is Djokovic’s lowest ranked loss since May 2004 when he lost to Melle Van Gemerden 6-2 4-6, 3-6. He was ranked number 569 while Djokovic was ranked even lower at 572.

Reilly Opelka sets new record at Brisbane International after beating Novak Djokovic

Opelka secured the biggest win of his career by taking Djokovic out of the Brisbane International.

In the process, he is now the lowest ranked semi-finalist in the tournament’s history and he will face his fellow big server Giovanni Mpetshi Perricard in the last four.

It has been a long journey for Opelka to return to full fitness after a nightmare run of injuries over the past two seasons, but he is hoping those days are now firmly behind him.

“It has been tough,” Opelka said about his injury woes. “A lot of doubt. I watched Taylor, Tommy, Frances, Ben on TV do great and that was fun and motivating. It kept me motivated in the sport.

“I watched Novak become the greatest in my two-year period off. You ask yourself what would Novak be doing in my position. That is the impact he has had on the sport.

“I stayed the course when I was on crutches and just hoped I would have another chance out here like I had tonight.”

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