Angelique Kerber was knocked out in the first round of the Italian Open in Rome on Tuesday in a 6-3, 6-1 defeat to Czech Katerina Siniakova - while Stan Wawrinka also suffered a straight-sets loss, falling to Italian teenager Lorenzo Musetti 6-0, 7-6(2).
Kerber, who reached the last-16 at the US Open, lasted only 69 minutes on the clay court as Siniakova advanced in straight sets with five breaks of serve.
Kerber was almost bageled in the second set before she saved three match points to break for the first time in the contest but Siniakova broke back in the next game to seal victory.
On the men's side of the draw, Wawrinka, seeded tenth, was served up a bagel in the first set, and though he made a better fist of the second, he could not compete with the Italian.
Musetti won 73 per cent of his points on his second serve, and took four of his seven break point opportunities to claim his first win on the ATP Tour.
Meanwhile, teenage sensation Coco Gauff, playing in her first ever main draw match on clay, came back from 4-2 down in the opening set to beat Tunisian Ons Jabeur 6-4, 6-3.
Gauff suffered first-round exits at the two hardcourt events in New York (the Western and Southern Open and the US Open) but put those defeats behind her to move into the second round in Rome.
"I'm definitely happy to get a win today, especially after a couple of tough losses back in New York," Gauff said. "I'm just happy to be playing."
Elsewhere, Denis Shapovalov and Andrey Rublev cruised into the second round with emphatic straight sets victories.
Canadian 12th seed Shapovalov, who reached the US Open quarter-finals last week, shook off jet lag to beat Guido Pella 6-2, 6-3, firing seven aces and 23 winners past the Argentine.
"Guido is definitely not an easy match, especially on this surface," Shapovalov said.
"I'm struggling with jet lag a little bit, especially with the matches I've had. But I'm trying to do everything I can to recover, I think I played at a high level today."
Ninth seed Rublev, making his debut at the Foro Italico, beat qualifier Facundo Bagnis 6-4, 6-4 to book a spot in the second round where he will face Hubert Hurkacz.
Rublev also reached the quarter-finals at Flushing Meadows last week and the 22-year-old Russian is looking to build on his stellar year having started the season with two hardcourt titles in Adelaide and Doha before the Covid-19 shutdown.
Alex de Minaur, another quarter-finalist at the US Open, was knocked out by Dominik Koepfer with the German fighting back from a set down to win 3-6, 6-3, 7-6(5).
Additional reporting courtesy of Reuters