Switzerland's Stan Wawrinka crashed out of the Italian Open in the first round on Tuesday after a humiliating defeat to 18-year-old Italian Lorenzo Musetti.

The three-time Grand Slam winner, the 10th seed in Rome, lost 6-0, 7-6 (7/2) against a player ranked 249th in the world.

Wawrinka, at 35 the oldest player in the tournament, fought back after trailing 2-0 in the second set, but it was already too late to regain control. 

Musetti had only played one tour-level match before ­facing the former world No.3 in Rome, ousting Wawrinka after one hour and 24 minutes.

"I have seen him play on television and I know he is a very tough player," said ­Musetti, who will next meet Kei Nishikori in the second round.

"I'm going to enjoy the victory before I start thinking about my match against Nishikori."

Musetti, the youngest player in the table, was born in 2002, the year Wawrinka took his first steps on the professional circuit. 

In the women's tournament, Spaniard Garbine Muguruza dispatched American Sloane Stephens in straight sets with Russian Svetlana Kuznestova battling through for her first win since the tennis restart.

Muguruza, the 2016 French Open champion and seeded ninth in Rome, eased through 6-3, 6-3 behind closed doors on the red clay at the Foro Italico.

Former French Open winner Kuznetsova had a tougher battle with American Bernarda Pera before pulling through 3-6, 7-6 (7/3), 6-3.

The two-time Grand Slam champion came from a set and a break down and a 3-0 deficit in the tiebreak to set up a meeting with Estonian 14th seed Anett Kontaveit.

The Rome tournament is a tuneup for the French Open in Roland Garros from September 27.