Injury-hampered Novak Djokovic moved into the third round of the Australian Open on Thursday as the path to a 22nd Grand Slam title opened up for him with the premature exit of second seed Casper Ruud.
Ruud's second-round exit came a day after Djokovic's great rival Rafa Nadal, the top seed, had been evicted after suffering a hip flexor injury that will sideline him for up to two months.
Nine-times Melbourne Park champion Djokovic was delayed only slightly by an inspired second set from French qualifier Enzo Couacaud in his 6-1 6-7(5) 6-2 6-0 victory but was troubled by his heavily-strapped left thigh.
With world number one Carlos Alcaraz absent injured, Djokovic will fear few opponents on the blue courts where he is unbeaten since 2018 but only if his hamstring holds out.
"I have to take it day-by-day. I am worried. I cannot say that I'm not. I have reason to be worried," said the Serbian.
"My physio and medical team have been doing everything possible so that I can be able to play every match. There's not much more to talk about. There's two choices: leave it or keep going. So I'm going to keep going."
Andy Murray, who Djokovic has beaten in four Australian Open finals, remains in the hunt after coming through a late-night epic against Australia's Thanasi Kokkinakis, winning 4-6 6-7(4) 7-6(5) 6-3 7-5 victory after five hours and 45 minutes – the second longest match in the tournament's history.
Former world number one Murray, who has defied medical logic to continue his career with a partly metal hip, trailed 5-2 in the third set before digging himself out of a hole to mark his 250th Grand Slam match with his 11th victory from a two-set deficit.
The match finished at 4.05am local time, after which the 35-year-old Murray said: "I think now we should all go to bed."
Women's second seed Ons Jabeur also departed after an error-strewn performance against former French Open finalist Marketa Vondrousova, but there were wins for title contenders Aryna Sabalenka, Caroline Garcia and Belinda Bencic.
Ruud was simply outplayed for all but a few games of his 6-3 7-5 6-7(4) 6-2 loss to 22-year-old Brooksby over nearly four hours on Rod Laver Arena.
"I didn't feel like I played particularly bad," said Ruud. "He just ended up winning many of the longer rallies and had sort of an answer to all the questions that I asked him."
Brooksby's win was followed by lucky loser Michael Mmoh stunning German former world number two Alexander Zverev 6-7(1) 6-4 6-3 6-2 to make it eight American men in the third round.
"I think we all push each other to really get better, regardless of each guy's situation," said Brooksby.
"I think that's shown in a lot of the guys having strong results lately."
Eighth seed Taylor Fritz was unable to join the American charge as he was upset 6-7(4) 7-6(2) 6-4 6-7(6) 6-2 by Australian Alexei Popyrin, while Danish ninth seed Holger Rune despatched Californian Maxime Cressy 7-5 6-4 6-4.
There was also early American success in the women's draw when Katie Volynets stunned ninth seed Veronika Kudermetova 6-4 2-6 6-2 to become the first U.S. qualifier to reach the third round since Lindsay Davenport in 1993.
Shelby Rogers, however, was no match for Belarusian Sabalenka, who recovered from a slow start to power past the American 6-3 6-1.
French fourth seed Garcia likewise came through a potentially tricky tie against former US Open finalist Leylah Fernandez 7-6(5) 7-5, while Bencic continued her fine form with a 7-6(3) 6-3 win over American Claire Liu.
Magda Linette joined fellow Pole and top seed Iga Swiatek in the third round with a 3-6 6-3 6-4 upset of 16th seed Anett Kontaveit, while Croatian Donna Vekic downed 18th seed Liudmila Samsonova 6-3 6-0.
Jabeur, though, was a shadow of the player who reached the finals at Wimbledon and the US Open last year, making 50 unforced errors in her 6-1 5-7 6-1 loss to Vondrousova.
Andrey Rublev continued to carve his way through the men's draw with a 6-2 6-4 6-7(2) 6-3 win over Emil Ruusuvuori, the third-set setback coming after a row with the umpire over whether the fifth seed was swearing in Russian.
He will next face Briton Dan Evans, who beat Jeremy Chardy 6-4 6-4 6-1 after the Frenchman also fell out with the chair official when a ball dropped from his pocket during a rally.
After two days of severe weather disruptions, Melbourne Park escaped extreme heat or rain on Thursday with play continuing well into the early hours of the morning to get the second round completed on schedule.