New York - 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."US Open results on Monday, the first day of the 2018 tournament at Flushing Meadows (x denotes seeded player):
Rafael Nadal (ESP x1) bt David Ferrer (ESP) 6-3, 3-4 - retired
Vasek Pospisil (CAN) bt Lukas Lacko (SVK) 7-5, 6-3, 6-2
Lorenzo Sonego (ITA) bt Gilles Muller (LUX) 7-6 (7/2), 6-7 (9/11), 5-7, 7-6 (8/6), 6-2
Karen Khachanov (RUS x27) bt Albert Ramos (ESP) 6-3, 6-2, 6-3
Jack Sock (USA x18) bt Guido Andreozzi (ARG) 6-0, 7-6 (7/4), 6-2
Nikoloz Basilashvili (GEO) bt Aljaz Bedene (SLO) 6-2, 4-6, 6-2, 2-6, 6-4
Guido Pella (ARG) bt Casper Ruud (NOR) 6-4, 6-4, 6-1
Paolo Lorenzi (ITA) bt Kyle Edmund (GBR x16) 4-6, 6-4, 7-5, 6-1
Dominic Thiem (AUT x9) bt Mirza Basic (BIH) 6-3, 6-1, 6-4
Steve Johnson (USA) bt Denis Istomin (UZB) 6-3, 7-6 (8/6), 6-3
Taylor Fritz (USA) bt Mischa Zverev (GER) 4-6, 2-6, 6-4, 7-6 (7/2), 6-2
Jason Kubler (AUS) bt Roberto Bautista Agut (ESP x19) 6-3, 6-3, 6-4
Denis Shapovalov (CAN x28) bt Felix Auger-Aliassime (CAN) 7-5, 5-7, 4-1 - retired
Andreas Seppi (ITA) bt Sam Querrey (USA) 6-7 (6/8), 6-4, 6-2, 2-1 - retired
Jeremy Chardy (FRA) bt Andrey Rublev (RUS) 6-2, 4-6, 6-4, 6-1
Kevin Anderson (RSA x5) bt Ryan Harrison (USA) 7-6 (7/4), 5-7, 4-6, 6-3, 6-4
Juan Martin del Potro (ARG x3) bt Donald Young (USA) 6-0, 6-3, 6-4
Denis Kudla (USA) bt Matteo Berrettini (ITA) 6-4, 7-5, 6-2
Andy Murray (GBR) bt James Duckworth (AUS) 6-7 (5/7), 6-3, 7-5, 6-3
Fernando Verdasco (ESP x31) bt Feliciano Lopez (ESP) 6-2, 7-5, 6-4
Borna Coric (CRO x20) bt Florian Mayer (GER) 6-2, 6-2, 5-7, 6-4
Roberto Carballs (ESP) bt Mitchell Krueger (USA) 3-6, 6-2, 6-4, 7-6 (7/3)
Daniil Medvedev (RUS) bt Evgeny Donskoy (RUS) 7-5, 6-4, 6-2
Stefanos Tsitsipas (GRE x15) bt Tommy Robredo (ESP) 6-3, 7-6 (7/1), 6-4
John Isner (USA x11) bt Bradley Klahn (USA) 7-6 (7/3), 6-3, 6-4
Nicolas Jarry (CHI) bt Peter Gojowczyk (GER) 7-6 (7/4), 4-6, 6-1, 7-5
Cameron Norrie (GBR) bt Jordan Thompson (AUS) 7-5, 4-6, 6-4, 6-3
Dusan Lajovic (SRB) bt Damir Dzumhur (BIH x24) 3-6, 6-1, 6-3, 6-4
Milos Raonic (CAN x25) bt Carlos Berlocq (ARG) 7-6 (7/4), 6-4, 1-6, 6-3
Gilles Simon (FRA) bt Lloyd Harris (RSA) 6-2, 6-2, 6-3
Ugo Humbert (FRA) bt Collin Altamirano (USA) 6-3, 7-6 (7/4), 6-3
Stan Wawrinka (SUI) bt Grigor Dimitrov (BUL x8) 6-3, 6-2, 7-5
Kaia Kanepi (EST) bt Simona Halep (ROM x1) 6-2, 6-4
Jil Teichmann (SUI) bt Dalila Jakupovic (SLO) 6-3, 6-0
Vania King (USA) bt Natalia Vikhlyantseva (RUS) 7-6 (7/4), 6-3
Rebecca Peterson (SWE) bt Anastasia Pavlyuchenkova (RUS x27) 1-6, 6-4, 6-3
Serena Williams (USA x17) bt Magda Linette (POL) 6-4, 6-0
Carina Witthoeft (GER) bt Caroline Dolehide (USA) 6-3, 7-6 (8/6)
Camila Giorgi (ITA) bt Whitney Osuigwe (USA) 6-4, 6-1
Venus Williams (USA x16) bt Svetlana Kuznetsova (RUS) 6-3, 5-7, 6-3
Garbine Muguruza (ESP x12) bt Zhang Shuai (CHN) 6-3, 6-0
Karolina Muchova (CZE) bt Dayana Yastremska (UKR) 6-4, 6-2
Lucie Safarova (CZE) bt Petra Martic (CRO) 6-4, 6-4
Ashleigh Barty (AUS x18) bt Ons Jabeur (TUN) 6-1, 6-3
Maria Sakkari (GRE x32) bt Asia Muhammed (USA) 6-3, 6-3
Sofia Kenin (USA) bt Madison Brengle (USA) 6-0, 4-6, 7-6 (7/4)
Ana Bogdan (ROM) bt Marie Bouzkov (CZE) 6-4, 6-2
Karolina Pliskova (CZE x8) bt Zarina Diyas (KAZ) 6-4, 7-6 (7/4)
Sloane Stephens (USA x3) bt Evgeniya Rodina (RUS) 6-1, 7-5
Anhelina Kalinina (UKR) bt Kathinka Von Deichmann (LIE) 1-6, 7-6 (7/0), 5-2 - retired
Victoria Azarenka (BLR) bt Viktoria Kuzmova (SVK) 6-3, 7-5
Daria Gavrilova (AUS x25) bt Sara Sorribes (ESP) 6-0, 6-0
Barbora Strycova (CZE x23) bt Danielle Lao (USA) 6-3, 6-4
Lara Arruabarrena (ESP) bt Kateryna Kozlova (UKR) 6-0, 6-3
Vera Lapko (BLR) bt Kateryna Bondarenko (UKR) 6-3, 6-3
Elise Mertens (BEL x15) bt Kurumi Nara (JPN) 6-2, 6-7 (5/7), 7-5
Julia Goerges (GER x9) bt Anna Kalinskaya (RUS) 6-2, 6-7 (5/7), 6-2
Ekaterina Makarova (RUS) bt Heather Watson (GBR) 6-1, 3-6, 6-3
Claire Liu (USA) bt Polona Hercog (SLO) 7-6 (7/4), 1-6, 6-4
Anastasija Sevastova (LAT x19) bt Donna Vekic (CRO) 6-2, 2-6, 6-3
Wang Qiang (CHN) bt Magdalena Rybarikova (SVK x31) 6-2, 6-2
Irina-Camelia Begu (ROM) bt Jennifer Brady (USA) 6-3, 6-3
Tatjana Maria (GER) bt Agnieszka Radwanska (POL) 6-3, 6-3
Elina Svitolina (UKR x7) bt Sachia Vickery (USA) 6-3, 1-6, 6-1