PARIS - Rafael Nadal was locked in a French Open quarter-final tussle with Argentinian Diego Schwartzman when rain ended play on Wednesday, after Garbine Muguruza thrashed Maria Sharapova to reach a last-four showdown with top seed Simona Halep.

World number one Nadal lost his first set at Roland Garros in three years, and when bad weather first interrupted the match the 10-time champion was in serious trouble with Schwartzman up a break in the second. The players briefly returned to the court, giving the 32-year-old Spaniard enough time to reel off three straight games, but the rains came again for a second and final time when he was serving for the set. The match will resume on Thursday with Schwartzman leading 6-4, 3-5 (15-30).

The winner of the match will play either third seed Marin Cilic or Schwartzman's compatriot Juan Martin del Potro. Their last-eight match was level at 6-6 (5/5) in a first-set tie-break on Court Suzanne Lenglen after Del Potro had earlier missed five break points.

Nadal had won 37 consecutive sets at Roland Garros since his 2015 quarter-final defeat by Novak Djokovic, but dropped serve three times to the enterprising Schwartzman in an exciting opener. The 25-year-old took his third set point with a rasping forehand up the line, after being made to wait when a spectator fell ill in the stands. Nadal made 14 unforced errors and struck just four winners in a poor first set, before having both of his wrists strapped by the trainer.

Schwartzman, who had never even reached a Grand Slam quarter-final until last year's US Open, broke first in the second set as Nadal uncharacteristically blew a 40-15 lead, capped by two wild forehands. The Court Philippe Chatrier, which was half-full during Muguruza's dismantling of Sharapova earlier in the afternoon, was packed with a crowd living every point when rain started to fall. Play continued though, with the set following a similar pattern to the first, as Nadal broke back before dropping his serve to 15.

The players were forced off the court for 40 minutes, but when they returned Nadal levelled for 3-3 and let out a trademark roar of 'vamos'. The Spaniard, who won five straight games after a rain delay to beat Alexander Zverev in the Rome Masters final last month, managed three in a row this time before play was ended for the day.

Muguruza condemned Sharapova to her heaviest Grand Slam defeat in more than six years and will face top seed Simona Halep for a place in the final against either Sloane Stephens or Madison Keys. The Spanish third seed, who was the champion in Paris in 2016, swept aside the Russian 6-2, 6-1 in just an hour and 10 minutes. Her semi-final with Halep will also decide the world number one spot next week.

Current number one Halep made the semi-finals for the third time by battling past Germany's Angelique Kerber 6-7 (2/7), 6-3, 6-2. Sharapova, playing at Roland Garros for the first time since 2015, suffered her most one-sided defeat at the Slams since a 6-3, 6-0 loss to Victoria Azarenka in the 2012 Australian Open final.

Sharapova made 27 unforced errors, was broken six times and served six double faults in only her fifth loss from 25 Grand Slam quarter-finals.

Two-time runner-up Halep came back from a set down for the second time in the tournament to see off 12th seed Kerber, who was bidding to become the first German woman in the last-four since Steffi Graf in 1999.