Ajla Tomljanovic drama leaves tennis world stunned at US Open

Ajla Tomljanovic has overcome a marathon first set to progress to her first ever US Open quarter final, joining fellow Australian Nick Kyrgios in achieving the feat on Monday.

Still coming down from an incredible triumph over Serena Williams which marked the end of the 23-time grand slam champion's illustrious career, Tomljanovic was down early against the in-form Ludmilla Samsonova.

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Having entered the fourth round clash riding a 13-match winning streak, Samsonova quickly raced to a 2-5 lead in the first set before Tomljanovic dug her heels in.

The Aussie hopeful recovered to 4-5 but was in deep trouble down 0-40 on her own serve, saving no less than seven set points to keep her first set hopes alive.

It took 18 minutes and a total of 30 points to hold serve but she did, eventually forcing a tiebreak at 6-6 that had had fans bracing for another brutal arm-wrestle.

And an arm-wrestle the tiebreak was, with Tomljanovic fending off a further eight set points before eventualy breaking through Samsonova's stiff opposition to win the tiebreak 13-11, a moment that left fans in utter disbelief.

The first set breakthrough fired Tomljanovic while Samsonova, who had won 18 consecutive sets heading into the match, struggled to regain the groove that helped her establish the early first set lead.

The Australian ultimately found a way to ride the emotions from the first set to victory, ultimately coming away with an impressive 7-7, 6-1 victory.

Tomljanovic has now reached back-to-back grand slam quarter-finals, after making the last eight at Wimbledon six weeks ago for the second year in a row.

Guaranteed a new career-high ranking inside the world's top 35 after the Open, Tomljanovic will play either Tunisia's fifth-seeded Wimbledon runner-up Ons Jabeur or Russian Veronika Kudermetova for a place in the semi-finals on Wednesday (Thursday AEST).

Kyrgios and Tomljanovic, a long-time former couple, are the first Australian men and women to make the US Open quarters in the same year since Pat Cash and Wendy Turnbull in 1984.

Nick Kyrgios through to US Open quarterfinal after defeating Daniil Medvedev

Nick Kyrgios has once again made of a mockery of the rankings and blown the US Open wide open with a rollicking fourth-round win over world No.1 and defending champion Daniil Medvedev.

In an explosive encounter laced with controversy and drama, Kyrgios risked being defaulted and overcame a running verbal battle with the chair umpire before ousting the top seed 7-6 (13-11) 3-6 6-3 6-2 on Sunday night.

It was the Wimbledon runner-up's second defeat of Medvedev in three weeks and vaulted Kyrgios into the quarter-finals at Flushing Meadows for the first time.

At last realising his rich potential, the 27-year-old will play another Russian, Karen Khachanov for a semi-final berth on Tuesday (Wednesday AEST).

Now three wins away from breaking his grand slam title duck, Kyrgios was imperious at times.

He received a standing ovation from the Arthur Ashe Stadium crowd after winning a pulsating opening set that stretched more than hour.

Other times, he flirted with disaster.

He looked to have thrown away the first set after giving up a 4-2 lead and then a 4-1 advantage in the tiebreaker, not to mention threatening to hit the self-destruct button and engaging in an unnecessary, elongated exchange with Greek umpire Eva Asderaki-Moore.

After levelling the match at a set apiece, Medvedev received an extraordinary, possibly unprecedented, gift from Kyrgios.

After looking to have earned a break point in the second game of the third set, when Medvedev couldn't return a ball, Kyrgios ran around the net celebrating and hit the ball away for a mock winner.

Quite rightly, though, Asderaki-Moore awarded the point to Medvedev because the Russian's shot, while clearly not going over the net, was "still in play".

"I thought it was legal," Kyrgios said, shaking off the blunder, somewhat uncharacteristically, before breaking Medvedev on his next service game to claim a 3-1 lead, then going on to seize a two-sets-to-one lead.

Kyrgios turned the screws with another break in the third game of the fourth set, then received an audible obscenity the following game.

But it didn't matter as Kyrgios snared a double break and powered to a 20th victory in his past 23 matches after three hours and 53 minutes.

With AAP

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