Simona Halep reached the semi-finals of the Internazionali d'Italia with a comfortable win over Caroline Garcia on Friday.

The world number one eased to a 6-2 6-3 triumph to set up a clash with Maria Sharapova, who came through a marathon encounter with Jelena Ostapenko to progress to the last four.

Halep easily wrapped up a straight-sets win that - along with Caroline Wozniacki's defeat against Anett Kontaveit - guarantees she will remain at the top of the rankings.

Having benefited from Madison Keys' withdrawal in the last round, the Romanian looked decidedly rusty as neither player held serve in the opening five games.

Eventually, however, Halep seized control. She reeled off three successive games to take the first set as Garcia's error-strewn performance made life easy for last year's beaten finalist in Rome.

Mistakes continued to plague the Frenchwoman in the second, although she did delay the inevitable by gaining a break back to make it 5-3, as Halep wrapped up victory with a backhand winner down the line.

Sharapova reached the semi-finals of the tournament for the first time since 2015 after outlasting reigning French Open champion Ostapenko in a thriller.

The unseeded Russian eventually prevailed 6-7 (8-6) 6-4 7-5 after three hours and 11 minutes on court, making it the longest match played on clay this season.

"It’s always nice to have a battle with a few ups and downs, and to finish strong," Sharapova told the media, according to the WTA Tour. "To get through a match like this against a really high-quality opponent and to end up winning it, I’m quite proud of the effort."

Both players had their service issues - they combined for 21 double faults - and while Ostapenko fought back from 5-2 down to draw level in the decider, Sharapova finished strongly to seal her first win over a top-10 player in 2018.