LONDON: Defending champion Serena Williams remained on course to retain her singles’ title at Wimbledon after reaching the fourth round with a 6-0, 7-5 win over Slovakia’s Dominika Cibulkova on Saturday.

Williams, who beat sister Venus in last year’s final here, has yet to drop a set in the first three matches of her title defence and she was far too strong for world number 46 Cibulkova.

The American top seed will face either 2004 Wimbledon champion Maria Sharapova or Barbora Zahlavova Strycova in the next round.

The three-time champion clearly has no intention of expending unnecessary energy in the first week of the tournament.

Serena had lost just five games in the previous two rounds at the All England Club - with her victory over Anna Chakvetadze in the second round taking just 49 minutes.

She had won the opening set in both her opening two matches without dropping a game and once again she set out to shatter her opponent’s resolve in the first set.

Meanwhile, Maria Sharapova has advanced to the fourth round for the first time since 2007, defeating Barbora Zahlavova Strycova of the
Czech Republic 7-5, 6-3.

The 23-year-old Russian will play three-time champion Serena Williams on Monday for a berth in the quarterfinals.

Sharapova, the 2004 champion, secured the victory Saturday with an ace after nearly two hours on court to advance to the final 16 at the All England Club. Sharapova gained the decisive break in the second set in the sixth game, after wasting five opportunities, then held the following game after saving a break point.