New York - Five-time champion Roger Federer strolled into the US Open third round on Thursday as fellow old-timer Lleyton Hewitt bid farewell in trademark, fighting style.
On a dramatic day which saw a record created for the longest women's match, and a new Grand Slam high for retirements from the men's tournament, Andy Murray escaped his earliest exit in 10 years when he came back from two sets down to make the last 32.
World number two Federer, the 17-time Grand Slam champion, needed just 80 minutes to rout Belgium's Steve Darcis 6-1, 6-2, 6-1.
The 34-year-old Swiss star, who was champion from 2004-2008 and runner-up in 2009, goes on to face German 29th seed Philipp Kohlschreiber.
Federer has lost just nine games in the first two rounds, his fewest in 16 appearances.
"Very often I started this tournament quite strong. It's always gone quite well for me," said Federer.
"I've always enjoyed conditions here, the balls, the speed of the court, the atmosphere in the arena. It's always worked very well for me."
Third seed and 2012 champion Murray came back from two sets down to defeat tiring Frenchman Adrian Mannarino 5-7, 4-6, 6-1, 6-3, 6-1 on Arthur Ashe Stadium.
Murray goes on to face Brazilian 30th seed Thomaz Bellucci for a place in the last 16.
"It was extremely tough. He hits the ball really flat, has fantastic timing on both sides and it was hard to read the ball in the first two sets," said 28-year-old Murray.
Murray, who had needed four sets to beat Nick Kyrgios in the opening round, fired 21 aces - the last of which was on match point - while Mannarino was undone by 61 unforced errors.
Former world number one Hewitt, the champion in 2001, made a dramatic farewell battling from two sets down and having two match points before losing to fellow Australian Bernard Tomic on a rocking Grandstand court.
In his final match in New York, the 34-year-old fell 6-3, 6-2, 3-6, 5-7, 7-5 after three hours and 27 minutes after his 57th career five-set match.
Hewitt will retire after January's Australian Open.
"He's a huge legend for me," said Tomic. "A lot of people think he's a great legend - what a privilege it was tonight for me."
America's Jack Sock and Denis Istomin retired from their matches as they wilted in the 33-degree Celsius (91.4 F) heat.
Twelve men - a record at the majors - as well as two women have now quit matches in the first four days.
The 22-year-old Sock was leading Belgium's Ruben Bemelmans 6-4, 6-4, 3-6, 1-2 when he started cramping and was forced to retire.
Sock, the 28th seed, collapsed on the court, where he was treated with ice packs by US Open medical staff before being helped off to the shade of the Grandstand.
Bemelmans next plays fifth-seeded French Open champion Stan Wawrinka who beat South Korean teenager Hyeon Chung 7-6 (7/2), 7-6 (7/4), 7-6 (8/6).
Istomin called it quits on Court Seven against Austrian 20th seed Dominic Thiem, who was 6-4, 6-4, 1-0 up at the time, with his win coming on his 22nd birthday.
The carnage led again to suggestions that the men, who play the best of five sets, should be accorded the same heat protection as women players.
The WTA allows a 10-minute break between the second and third sets of women's matches when the mercury bursts through 30.1 degrees.
"When it's extremely hot and humid, it helps to have that break," said Murray.
"You get the chance to sort of go off and change, get under a cold shower if you want to."
Britain's world number 97 Johanna Konta made history when she defeated Wimbledon runner-up Garbine Muguruza in the longest women's match in US Open history.
"I thought it would be really embarrassing if I just toppled over there," said Konta, who won 7-6 (7/4), 6-7 (4/7), 6-2 in 3 hours 23 minutes in the hottest part of the day.
It beat by seven minutes the previous longest match record set in 2011 when Samantha Stosur defeated Nadia Petrova.
Sydney-born Konta has now won 15 matches in a row since Wimbledon and goes on to tackle German 18th seed Andrea Petkovic for a place in the last 16.
Ninth seeded Muguruza became the fifth top-10 seed to crash out of this year's tournament before the third round.
With Maria Sharapova having withdrawn through injury on the eve of the season's concluding Grand Slam, the women's draw was down to its bare bones.
Top seed Serena Williams made the last 32 on Wednesday and was joined on Thursday by second seed Simona Halep and fifth-seeded Petra Kvitova.
Halep advanced by defeating Ukraine's Kateryna Bondarenko 6-3, 6-4 while fifth seed and two-time Wimbledon champion Kvitova saw off Nicole Gibbs of the United States 6-3, 6-4.
US Open results on Thursday, the fourth day of the 2015 tournament at Flushing Meadows (x denotes seeded player):
Stan Wawrinka (SUI x5) bt Hyeon Chung (KOR) 7-6 (7/2), 7-6 (7/4), 7-6 (8/6)
Ruben Bemelmans (BEL) bt Jack Sock (USA x28) 4-6, 4-6, 6-3, 2-1 - retired
Viktor Troicki (SRB x22) bt Rajeev Ram (USA) 7-6 (12/10), 6-4, 3-6, 6-3
Donald Young (USA) bt Aljaz Bedene (GBR) 3-6, 6-4, 6-4, 6-2
Kevin Anderson (RSA x15) bt Austin Krajicek (USA) 6-3, 6-4, 6-2
Dominic Thiem (AUT x20) bt Denis Istomin (UZB) 6-4, 6-4, 1-0 - retired
Thomaz Bellucci (BRA x30) bt Yoshihito Nishioka (JPN) 6-0, 6-3, 6-4
Andy Murray (GBR x3) bt Adrian Mannarino (FRA) 5-7, 4-6, 6-1, 6-3, 6-1
Tomas Berdych (CZE x6) bt Jurgen Melzer (AUT) 7-6 (7/2), 6-1, 6-3
Guillermo Garca-Lpez (ESP x31) bt Nicolas Mahut (FRA) 6-4, 6-2, 6-7 (4/7), 6-1
Bernard Tomic (AUS x24) bt Lleyton Hewitt (AUS) 6-3, 6-2, 3-6, 5-7, 7-5
Richard Gasquet (FRA x12) bt Robin Haase (NED) 4-6, 6-3, 7-6 (7/4), 6-4
John Isner (USA x13) bt Mikhail Youzhny (RUS) 6-3, 6-4, 6-4
Jiri Vesely (CZE) bt Ivo Karlovic (CRO x21) 7-6 (7/3), 3-6, 3-6, 6-2, 7-6 (7/4)
Philipp Kohlschreiber (GER x29) bt Luks Rosol (CZE) 7-6 (7/4), 6-2, 6-2
Roger Federer (SUI x2) bt Steve Darcis (BEL) 6-1, 6-2, 6-1
Petra Kvitova (CZE x5) bt Nicole Gibbs (USA) 6-3, 6-4
Anna Karolina Schmiedlova (SVK x30) bt Danka Kovinic (MNE) 6-4, 5-7, 6-4
Andrea Petkovic (GER x18) bt Elena Vesnina (RUS) 6-3, 7-6 (7/4)
Johanna Konta (GBR) bt Garbie Muguruza (ESP x9) 7-6 (7/4), 6-7 (4/7), 6-2
Sara Errani (ITA x16) bt Jelena Ostapenko (LAT) 0-6, 6-4, 6-3
Samantha Stosur (AUS x22) bt Evgeniya Rodina (RUS) 6-1, 6-1
Flavia Pennetta (ITA x26) bt Monica Niculescu (ROM) 6-1, 6-4
Petra Cetkovska (CZE) bt Caroline Wozniacki (DEN x4) 6-4, 5-7, 7-6 (7/1)
Varvara Lepchenko (USA) bt Lesya Tsurenko (UKR) 7-6 (9/7), 6-2
Mona Barthel (GER) bt Olga Govortsova (BLR) 2-6, 6-2, 6-4
Victoria Azarenka (BLR x20) bt Yanina Wickmayer (BEL) 7-5, 6-4
Angelique Kerber (GER x11) bt Karin Knapp (ITA) 7-5, 6-2
Barbora Strycova (CZE) bt Qiang Wang (CHN) 6-2, 4-6, 7-5
Sabine Lisicki (GER x24) bt Camila Giorgi (ITA) 6-4, 6-0
Shelby Rogers (USA) bt Kurumi Nara (JPN) 6-4, 6-4
Simona Halep (ROM x2) bt Kateryna Bondarenko (UKR) 6-3, 6-4