Daniil Medvedev's Rome Open title defense came to an early end on Tuesday after the world number four was knocked out at the last-16 stage by Tommy Paul, while Iga Swiatek cruised into the women's semifinals.

Second seed Medvedev has never successfully defended an ATP Tour crown and was well below his best, stunned in straight sets 6-1, 6-4 by American Paul who claimed his first win against the former U.S. Open champion.

"Mentally I had to be much better. I started to calm myself down and focus on the match only at the end of the match, and it was too late," Medvedev told reporters.