Andy Murray went down scrapping in a bruising three-set defeat to Fabio Fognini on Tuesday at the Shanghai Masters, while Roger Federer enjoyed a straight-sets win over Albert Ramos-Vinolas.
In a bad-tempered match that stretched past three hours, Murray and Fognini confronted one another near the end at the crossover.
The Italian plays the unseeded American Taylor Fritz or Russian seventh seed Karen Khachanov in the last 16 after a 7-6, 2-6, 7-6 victory.
It came hours after the Australian Open said the former No 1 Murray will make his return to Grand Slam tennis there in January, a year after a career-saving hip operation.
The Briton says that his hip is now fine but he needs to build up his match fitness and speed across the court.
The three-time grand slam winner will be pleased at how he was able to go toe-to-toe with Fognini even as the match clock ticked past three tough hours on court.
But he will be kicking himself for failing to put Fognini away when he was serving for the match at 6-5 in the third set.
The Fognini and Murray, both 32, had a lengthy exchange at the net and bad blood boiled between them throughout. They shared the briefest of handshakes at the end.
Murray accused his opponent of shouting during a critical point in the match. He said: "Someone made a noise, I didn't know who made the noise, I looked in the direction of where the noise came from.
"He then told me, 'Stop looking at me, what are you looking at me for?'
"I was like, 'I was just about to hit a shot and someone made a noise'. He then told me to stop looking at him."
"The sound came from him, which you're not allowed to do, it's against the rules, it's hindrance, you shouldn't do it.
"Fabio wanted to engage with me, I probably shouldn't have done, but I am not having him talk to me like that on court."
Murray was also annoyed he repeatedly served for the match but failed to win. "I want to say that's the first time ever in my career that that's happened," he said. "I think it's the first time I served for a match twice and not won."
Ruthless Federer suffered no such problems against his Spanish opponent, winning 6-2, 7-6 to set up a last 16 clash with either Belgium's David Goffin or Mikhail Kukushkin of Kazakhstan.
The third-ranked Federer, 38, is looking to end the season on a high with a fourth title of the year – although he failed to win a 21st Grand Slam this season.
The 46th-ranked Ramos-Vinolas put up a better fight in the second set, forcing the tie break and taking a 2-0 and then 4-1 lead in it.
But cheered on by his band of local supporters, who held aloft banners proclaiming their hero "superhuman", Federer won the tie break – and the match – with a forehand smash.
Federer said a loss to the Spaniard in 2015 in Shanghai had driven him on.
"The truth, yeah, I was thinking about it, watched highlights," he said. "Remember how it felt, I had my chances. I won many more points that time than I lost, so I should have actually won that match."
Red-hot Daniil Medvedev, the US Open finalist, got his tournament off to a flying start with a 6-3, 6-1 demolition of Britain's Cameron Norrie.
The Serbian world No 1 Novak Djokovic takes on Denis Shapovalov of Canada in the second round today.
