It marked the first exhausting day in what could be a three-week tennis marathon for Williams, who will be hoping her long search to win an elusive 24th grand slam title – and equal Margaret Court’s record tally – will end on September 12 with victory in the US Open final.
On Monday, down 6-5 in the third set and with Rus serving for the match, a drained Williams looked down for the count but she picked herself up to break the Dutchwoman to force a deciding tiebreak. She then moved in for the kill to win it 7-0.
After working her way into the main draw through qualifying, Rus came in match sharp while Williams looked sluggish on a hot and humid New York afternoon. She spent much of the first set trying to tame a misfiring forehand.
While Williams fitness has been questioned, her fighting spirit has never been in doubt and never more than in the third set.
Naomi Osaka, seeded fourth here, beat Karolina Muchova 6-7 6-4 6-2.
In the men’s draw, the last remaining Australian, John Millman was eliminated in the second round by John Isner 4-6 7-6 7-6. Only three Australians travelled to New York: Millman, Alex de Minaur and Ajla Tomljanovic. Tomljanovic and de Minaur lost in the first round.
Third seed Daniil Medvedev launched the defence of his title with a tidy 6-4 6-4 second round win over Marcos Giron.
The subdued atmosphere and empty stands were far removed from a year ago when Medvedev entertained a capacity crowd with a startling fight back in the US Open final against Rafael Nadal before falling to the Spaniard in five-sets.
Playing in the shadow of the massive Arthur Ashe Stadium that will be centre stage when the U.S. Open gets underway next week, Medvedev delivered a workmanlike effort against the 101st ranked American on a Grandstand court, left empty by COVID-19 safety protocols.
“Mentally I didn’t prepare at all to play with no fans,” said Medvedev. “I would say it’s even easier to keep focused.”
Andy Murray claimed the biggest win of his comeback and a place in the last 16, taking out self-destructing fifth seed Alexander Zverev 6-3 3-6 7-5.
Working his way back to match fitness after undergoing a second round of hip surgery in January, Murray offered hope that he was on the right track with a tidy first-round win over Frances Tiafoe on Saturday.
Big-hitting Canadian Milos Raonic blasted 23 aces in 6-3 7-5 victory over Briton Daniel Evans.
But it was a bad day for the rest of the Canadian contingent, 12th seed Denis Shapovalov falling 7-6(4) 3-6 6-4 to Germany’s Jan-Lennard Struff while 15th seed Felix Auger-Aliassime was stopped 6-7(4) 6-2 7-6(5) by American Tennys Sandgren.
Australia’s world No.1 Ash Barty, as well as the 2011 US Open champion Sam Stosur, and Nick Kyrgios chose not to travel to New York.