World number one Serena Williams continued her undefeated run this season to reach the final of the Family Circle Cup with a 6-1, 7-5 win over Lindsay Davenport on Saturday.

Williams, who has won all of her 21 matches this year, will meet Justine Henin-Hardenne in Sunday's final.

Belgium's Henin-Hardenne advanced with an easy 6-2, 6-1 win over 17-year-old American Ashley Harkleroad in the other semi-final.

Davenport lost eight of the first nine games in the showdown between the two Americans and appeared to be headed for a quick exit.

But she rallied to get to within two points of taking the second set before Williams won the match, ending it with three powerful aces.

"I don't know how many errors I made or not, but that's how I would like to play tennis," Williams told reporters of her early domination.

"She totally raised the level of her game, completely, up four or five notches and caught up with me," Williams said. "Then we really were battling it out at the end."

"There wasn't a whole lot I could do," Davenport said. "It seemed like she was going for broke, and most of the time they were winners and a few times I got errors.

"I really felt like I was never really in control of too many points, if any."

Williams has now beaten Davenport five straight times as she continues her stranglehold on the sport. She is the defending champion of all four women's Grand Slams.

Henin-Hardenne, the fourth seed, used her powerful serve to subdue Harkleroad, who beat three seeded players en route to her first WTA semi-final appearance. The Belgian has defeated Williams once before in five career matches. "I have to play a tough opponent in the final, and I'll have to keep my fingers crossed," Williams said.

"I am definitely not taking anyone for granted. Justine is playing really good tennis and she always seems to do very well on the clay."

"She does not lose a lot of matches, so it's going to be a tough match for me," Henin-Hardenne said.