Relegated to Court No. 5, fourth-seeded Holger Rune failed to survive the US Open first round.
No. 8 seeded Maria Sakkari considers a break after suffering her third straight Grand Slam opening-round exit.
"The mental side was not that easy as restore the arm was," Dominic Thiem said.
The former champion has been dealing with a stress fracture in her back.
The 2014 US Open finalist has been snake-bitten by injuries.
The Spaniard suffered a spinal injury this spring and has been unable to recover.
US Open will celebrate Billie Jean King and 50th anniversary of equal prize money on Monday night.
