The former world number one battled from a set down to beat Denis Shapovalov (24) 4-6, 7-6(5), 6-3.

Murray, who snapped a six-match losing streak in Doha last week before going out against Czech teenager Jakub Mensik, told the BBC last December that 2024 could be his final year on the ATP Tour.

"I probably don't have too long left but I'll do as best as I can these last few months," said Murray on Monday.

"I still love competing and still love the game. Obviously, it gets harder and harder the older you get to compete with the young guys and keep your body fit and fresh."

Murray appeared to say to his player's box during his gruelling loss to Mensik last week that "this game is not for me anymore", but he played down those comments.

"People read a lot into what I say on the court sometimes and it's not always rational," he added. "But everyone asks me about it all the time anyway."

Murray clinched his 500th win on hard courts, joining Roger Federer, Novak Djokovic, Andre Agassi and Rafael Nadal in reaching the milestone.

"Yeah, it's not bad (500 hard-court wins). Hard courts have been a great surface for me over the years... I'm very proud of that."

Murray struggled to contain a powerful first-set display from former top-10 player Shapovalov, who is searching for his best form after missing the end of last season through injury.

But the three-time Grand Slam champion edged a second-set tie-break before easing through the decider with a double-break.

Murray will face either fellow veteran Gael Monfils or French fifth seed Ugo Humbert in the last 16.

The Briton has not reached the quarter-finals at an ATP event since his final loss to Daniil Medvedev in Qatar over a year ago.

Murray dropped 17 spots in the ATP rankings earlier on Monday, falling to 67th place.