Italian Berrettini is at a career-high ranking of 13 and is on course to qualify for next month's ATP Finals, so Murray's 7-6 (2) 7-6 (7) victory was hugely impressive considering the Scot only won his first ATP Tour match since January last week.Murray said on eurosport.co.uk: "It was a good one to get through. It was obviously pretty tight at the end of both sets."I think first set I probably served a little bit better at the end, and then the second set there was just a few sort of cat and mouse points at the end, which thankfully I came out on top of one or two more than him, but it was a very tight match and I thought I played pretty well."The victory is arguably Murray's best since his career-threatening hip problems emerged in the summer of 2017.It now appears increasingly likely the resurfacing operation he underwent eight months ago will allow him a second chance at his career.Murray recovered from a break down in both sets, breaking Berrettini when he served for the opener at 5-3 and then fighting back from an early deficit in the second.Berrettini had two chances to level the contest in the second-set tie-break but Murray saved both with bold net play and took his first match point.He will take on fellow British player Cameron Norrie in round two on Wednesday, and Murray said: "Hopefully I can have a good run here. That was a good start for me. I think I play again tomorrow so that will be a good test for me."It's the first time I will have played high-level back-to-back days, see how I pull up after that one. But it's a bit of progress for me again this week, which is good."I feel like the progress has been quite consistent and hopefully that keeps going through to the end of the year."
Elsewhere, Kyle Edmund suffered a fifth straight defeat, at the hands of 213-ranked wildcard player Zhizhen Zhang. The world number 34 went down 6-4 3-6 7-6 (7-5) on Monday to the Shanghai-born player. Edmund hasn't tasted victory since he defeated Nick Kyrgios at the Coupe Rogers in Montreal in August.
Dan Evans, ranked 48th in the world, faces John Isner in round two after the American defeated France's Gael Monfils. Evans defeated China's Zhe Li 6-3 6-4 to advance in the competition.