New York - Serena Williams launches yet another bid for Grand Slam history on Tuesday, part of a blockbuster second night of the US Open that also features men's second seed Andy Murray.
Williams, in search of a seventh US Open crown, opens the action under the floodlights on Arthur Ashe Stadium Court against Russian veteran Ekaterina Makarova.
The US superstar is seeking to add a second major title of 2016 to the Wimbledon crown she won in July. Her 23rd Grand Slam singles triumph would break the Open Era record she shares with Steffi Graf.
Hindered since Wimbledon by inflammation in her right shoulder, Williams needs a strong run in Flushing Meadows if she's to break Graf's 25-year-old record for consecutive weeks at world number one.
While Williams has struggled since beating Angelique Kerber in the Wimbledon final, Murray has gone from strength to strength since capturing his second title at the All England Club.
Fresh from a successful defence of his Olympic gold in Rio, Murray tackles Czech Lukas Rosol.
Murray has played down expectations the match could be a repeat of his last stormy meeting with Rosol in the quarter-finals at Munich in 2015.
Bumped by Rosol on a changeover, an incensed Murray told the Czech that he was "hated" on the ATP tour.
"I have actually gotten along fine with him apart from that day," Murray said. "He's a tough, tough opponent, a big, strong guy. He goes for his shots and takes a lot of risks."
Murray has reached the final in each of the year's first three majors, losing to world number one Novak Djokovic in Australia and Paris before beating Milos Raonic at Wimbledon.
DEL POTRO RETURNS
Men's third-seed Stan Wawrinka of Switzerland and two-time women's champion Venus Williams, seeded sixth, highlight the afternoon action on the massive Ashe court - where favorable weather forecasts indicate the new retractable roof won't be called into action until later in the week.
Wawrinka, who missed the Olympics with a back injury and crashed out of the third round of the hardcourt Masters tournament in Cincinnati, will try to turn his fortunes around against Spain's Fernando Verdasco.
Seven-time Grand Slam champion Venus Williams opens her account against Ukraine's Kateryna Kozlova.
Juan Martin del Potro, the 2009 US Open champion, launches his campaign against fellow Argentine Diego Schwartzman on the Louis Armstrong stadium court.
Del Potro, 27, earned a wild card invitation with a stirring run to the Olympic final in Rio, where he defied his world ranking of 141 to beat Novak Djokovic and Rafael Nadal on his way to the gold medal match.
Women's fourth seed Agnieszka Radwanska takes on American Jessica Pegula on the Armstrong court, while men's sixth seed Kei Nishikori of Japan opens Tuesday's action on the new Grandstand court against German Benjamin Becker.