Former world number one Andy Murray won his first match at a Grand Slam for 14 months on Monday and then revealed he has to spend seven hours a day to keep his repaired hip from breaking down.
Murray's 6-7 (5/7), 6-3, 7-5, 6-3 win over Australia's James Duckworth at the US Open was his first at the majors since Wimbledon in 2017.
He then missed last year's visit to New York before undergoing hip surgery in January, sitting out this year's Australian Open, Roland Garros and Wimbledon.
His return to Flushing Meadows, where he won the first of his three majors in 2012, represents just his fifth event of 2018.
As a consequence, the 31-year-old is being conservative on the practice courts but intense in the treatment room, especially when it comes to rehabbing his troubling hip.
"Last week when I was rehabbing after Cincinnati, I was two-and-a-half hours in the morning, and then an hour and a half in the pool in the afternoon, and then on top of that, treatment, which can be anywhere from two to three hours.
"Pretty intense, yeah," said Murray after seeing off world 448 Duckworth whose five surgeries tops Murray's three trips to the operating theatre.
Murray, in an effort to prolong his career, has trimmed back his famous work ethic on the courts, especially on the rest days at the Slams.
"Sometimes on the off-days at Slams I would hit for, like, an hour and a half. In my opinion, it's too much.
"I certainly won't be doing that in future. I will be keeping my practice on the off-days much lighter, and conserve as much energy as I can for the matches."
Despite his win on Monday, Murray again played down his chances of winning the title in New York.
For a player ranked a lowly 382 -- and with only five match wins under his belt since his return -- such caution is understandable.
"There's many, many things that I would have wanted to change to be considered a contender. I don't think anything changes after today," said Murray who next faces Spanish 31st seed Fernando Verdasco.
Murray has a 13-1 winning record over the 34-year-old Spaniard whose last win against the Briton at the 2009 Australian Open.
"Fernando is a great shot-maker and someone that when he's on his game, really tough to beat," said Murray.
"He has an extremely heavy forehand, plays with a lot of spin. On the serve, kind of difficult sometimes to know what he's going to do.
"I have played him some times where he's been going for huge serves. And then I also played in one, he served he served like 80% first serve and kind of rolled the serve in."