Safina struggles on

The top seed, who is aiming to win her first grand slam title, was unconvincing at times but did enough to see off the challenge of the world number 100 in one hour and 22 minutes on Court Two.

There were concerns over Safina's fitness heading into the clash, with the Russian hampered by a knee injury.

Although she looked slow at times around the court, Safina still found herself a break up in game four of the first set following a long forehand from De Los Rios.

The Paraguayan also faced a battle on her next service game, staving off four more break points, but Safina wrapped up the set three games later.

De Los Rios had produced several impressive forehands but was not really making an impact on Safina's serve.

The veteran Paraguayan showed signs of improvement in the second set though, and as the world number one struggled to get on top of the match, a stalemate ensued.

The first 10 games went with serve, but with the threat of a tie-break looming, Safina lifted her play in the 11th and it paid off when she secured a break point and then watched De Los Rios send a forehand wide.

That left the Russian serving for the match and she sealed the win with a lovely backhand.

Safina has already finished as runner-up at both the Australian Open and French Open in 2009 and has never gone beyond the third round at Wimbledon. She will be hoping to better that record this year, and faces Kirsten Flipkens of Belgium in her next match.