World number one Carlos Alcaraz suffered a shock third round defeat in the Italian Open at the hands of unheralded Hungarian Fabian Marozsan, losing 6-3, 7-6 (7/4) on Monday.

The 20-year-old Spaniard had come into the tournament on the back of wins in Barcelona and Madrid but was outplayed by Marozsan, who is ranked 135th in the world.

Marozsan, 23, won the final six points of the second-set tiebreaker to hand US Open champion Alcaraz a wake-up call with the French Open starting in less than a fortnight.

Marozsan, who next plays Borna Coric for a place in the quarter-finals, had not won a match on the ATP Tour prior to the tournament -- indeed this is the first time he has qualified for the main draw at a tournament on the Tour.

"Everything was perfect today, I was doing my job," the winner said. "I cannot imagine this win, even if it was my dream last night.

"I thought I might win a few games or a set.

"I tried to hit back every ball, I was trying to do my best."

Marozsan produced 24 winners in a victory which took an hour and three quarters.

"I had hoped I could do something special," he said. "Now I've just beaten the best in the sport so I'm very happy."

Alcaraz now stands 30-3 on the season as he prepares to head to Roland Garros as top seed for the first time at a Grand Slam.

In other results at the ATP-WTA tournament, sixth seed Andrey Rublev defeated Spain's Alejandro Davidovich Fokina 7-6 (10/8), 6-3.