Serena Williams remains on course to defend her Rome Masters title after comfortably dispatching of Zhang Shuai in their quarter-final match on Friday.

The 17-time Grand Slam champion took little over an hour to record a 6-1 6-3 victory at Foro Italico, where she will play Ana Ivanovic in the last four.

Williams broke in every one of Zhang's service games in the first set, although the Chinese did prevent a bagel by capitalising on a couple of mistakes from the American in the sixth game.

The world number one's fourth break earned her a set lead, but Zhang provided more of a test in the second as she held her own until a powerful Williams forehand clinched her a break and a 4-2 advantage.

From then on, Williams could go through the motions untroubled against an opponent who has never reached the second round of a Grand Slam, but tougher opposition will follow in the semi-finals.

Ivanovic knocked Williams out of the Australian Open in January 2014.