French Open champion Garbine Muguruza had to work hard to transfer her punch on Paris clay to Wimbledon's grass, beating Camila Giorgi 6-2 5-7 6-4 with a performance of powerful baseline tennis.

The Spanish world number two and her battling Italian opponent, ranked 65 places below, entertained the Centre Court with intense rallies of relentless ferocity.

It was the confidence and enormous serve of last year's runner-up Muguruza that that got the better of Giorgi - but not before the 24-year-old Italian had overcome bouts of inconsistency to force a forehand error and grab the second set.

The Spaniard, 22, finally put her foot down in the 10-minute third game of the third set, forcing six break points before finally wrestling the game from the underdog.

A big serve that Giorgi could only put wide won Muguruza the match and a clash with Slovak qualifier Jana Cepelova in the second round.

As she has done for most of the past 19 British summers, Venus Williams took a large, languid stride into the second round.

The oldest woman in the main singles draw, five-times champion Williams was at times sublime as she beat Croatian Donna Vekic 7-6 (7-3) 6-4 on a sunny Court One.

"I felt like I couldn't hit a winner against her today, she ran everything down and played amazing tennis," Williams said.

"The first set, there were some hairy moments there, down some set points, but I guess that's where experience sets in. I started to feel like maybe I had the chance to win the most important points."

In the tournament's first big surprise, former top-ranked Ana Ivanovic was beaten 6-2 7-5 by Ekaterina Alexandrova, a Russian qualifier ranked 223rd in the world and making her Grand Slam debut.

The Serb blamed a wrist injury for a surprise defeat to a player who had never played in a grand slam prior to this match.

"Yeah, it was very tough," Ivanovic said.

"I mean, for two weeks I've struggled with my right wrist. It was very hard to accelerate on my forehand. I tried to do everything possible to be fit and recover and tape it and so on.

"It was a little bit sore. I feel like it caused me a lot of mis-hits."