Rome, May 20 (IANS): Second-seeded Serbian Novak Djokovic had grabbed a 6-1, 1-2 lead over Argentine Juan Martin del Potro before their Italian Open tennis quarter-final match was suspended due to heavy rain.

The contest will resume early Saturday afternoon, tournament organisers said, reports Efe.

That could mean a long day at the office for the winner, who will have to play his semi-final match a few hours later against eighth-seeded Austrian Dominic Thiem.

Djokovic lost his opening service game to fall down 0-1 but rebounded quickly to win the next six games and take the first set in 44 minutes.

The Serbian's superior backhand was the difference in the opener, as he controlled the baseline rallies and struck 15 winners to the unseeded Argentine's six (none from his weaker wing).

Del Potro held serve twice and Djokovic once at the start of the second set before a heavy downpour at the Foro Italico sent the players to the locker room at around 10:45 pm.

Djokovic, the dominant player in men's tennis this time last year, is looking to get his game on track after a rough start to the 2017 season that included losses prior to the semi-final round at the Australian Open, Indian Wells and the Monte-Carlo Masters.

Earlier on Friday, 16th-seeded German Alexander Zverev and unseeded American John Isner set up a semi-final clash with victories over fifth-seeded Canadian Milos Raonic and sixth-seeded Croatian Marin Cilic, respectively.

Thiem pulled off an upset in Friday's third men's singles quarter-final match with his 6-4, 6-3 victory over seven-time champion Rafael Nadal, who suffered his first loss of the 2017 clay-court season.

Even so, with titles at the Monte-Carlo Masters, the Barcelona Open and the Madrid Open, the 30-year-old Spaniard will be the favourite to win Roland Garros for the 10th time.

The French Open, tennis' lone clay-court Grand Slam tournament, gets under way on May 28.