Melbourne, Jan 29 (IANS): American tennis great Serena Williams stayed on course to claim her sixth Australian Open women's singles title after sealing a straight sets win over compatriot Madison Keys in the semifinals here Thursday.

The 18 time Grand Slam champion won 7-6(5), 6-2 in one hour and 24 minutes to exact sweet revenge for her older sister Venus' elimination in the quarters by Keys Wednesday, reports Xinhua.

Though Williams broke only three times in two sets, she lost serve just once. After wasting seven matchpoints in the seventh game of the second set, the top seed converted on the eighth with an ace.

"She pushed me really hard in the first set and I had to really dig deep mentally to get through that. It was a little frustrating. I had like nine or 10 matchpoints and couldn't close it out. That doesn't happen so much. She played like she didn't have anything to lose," Williams said.

"It's really great to be in the final again and I didn't come here with that expectation so it's really exciting."

Williams will face Maria Sharapova in the final Saturday.