Defending champion Iga Swiatek was bundled out of the Italian Open by American Danielle Collins, who beat the Polish world number two 6-1 7-5 in the round of 32 on Saturday.
Five-time Grand Slam champion Swiatek went 5-0 down in the opening set before managing to get on board and avoid an embarrassing bagel.
While the first set was all one-way traffic, the second was level at 4-4 before 2022 Australian Open runner-up Collins pulled away with the win in one hour and 44 minutes.
Swiatek, who held a commanding 7-1 head-to-head record against Collins before heading into the contest, has not won a tournament in almost a year.
“I played Iga so many times. The winning favour is in her favour. When you play that many close matches and play some of your best tennis but lose, you learn a lot. I feel like I applied that today,” Collins, 31, said.
