Mónica Puig has registered the first major upset at Wimbledon…

The 19-year-old Puerto Rican tennis player hit 38 winners to defeat Italy’s Sara Errani, the tournament’s fifth seed, 6-3, 6-2 on Monday in the first match on Court 18 of the grass-court Grand Slam tournament.

Puig, playing in her first grass-court tournament as a professional, completely outplayed Errani with her hard-hitting baseline game.

Errani was the runner-up at last year’s French Open and had reached at least the semifinals of three of the last five Grand Slams. But on the slick grass at the All England club on Monday, she had only 13 winners and was broken four times.

Puig squandered five match points before hitting a forehand winner past Errani to close out the match. She then dropped her racket to the turf and covered her face in her hands.

Errani withdrew from last week’s grass-court warmup at Eastbourne with a leg injury, but showed no signs of any physical problems during the match.

It’s the third time a top-5 women’s seeded player has lost in the first round at Wimbledon since 2001. The others were Martina Hingis in 2000 and Francesca Schiavone in 2010.

Monday’s defeat marked another humbling Wimbledon exit for Errani.

Last year, the Italian went an entire set without winning a point in losing 6-0, 6-4 in the third round to Yaroslava Shvedova of Kazakhstan. Shvedova was the first player in a Grand Slam to achieve a so-called “golden set” by winning 24 straight points.

Puig reached her first WTA main draw quarterfinal at the 2013 Portugal Open. She defeated number 8 seed and former top-15 player Julia Görges in round one before beating former French Open champion Francesca Schiavone in the second round. She lost in the quarterfinals to number 4 seed Carla Suárez Navarro of Spain.

At the 2013 French Open, Puig had the most remarkable win of her career before her big Wimbledon win when she defeated world number 11, Nadia Petrova, in three sets.

She next faces Spain’s Silvia Soler Espinosa in the second round.