MELBOURNE: Venus Williams has reached her 21st Grand Slam semi-final, her first at the Australian Open in 14 years.

CoCo Vandeweghe advanced to her first major semi-final, anywhere, beating Grand Slam winners in back-to-back rounds. The one sure outcome when they meet this week will be an American in the final at Melbourne Park.

The 36-year-old Williams beat No. 24-seeded Anastasia Pavlyuchenkova 6-4, 7-6 (3) on Tuesday, becoming the oldest player to reach the Australian Open women's semi-finals in the Open era.

She'll be meeting a confident Vandeweghe, who dictated play against French Open champion Garbine Muguruza in a 6-4, 6-0 quarter-final win.

The No. 35-ranked Vandeweghe upset top-ranked Angelique Kerber, who won the Australian and US titles last year, in the fourth round. She followed it up with another commanding win, the 10th in her career against a Top 10 player.

Vandeweghe saved the only break point she faced in the first set with an ace, and only conceded 10 points in the 28-minute second set. Of her 31 winners, 14 were from her powerful forehand side.

"Once I got rolling in the second, it was like a freight train," she said, "You couldn't stop it."

Williams has advanced through the tournament without dropping a set, and isn't ready to stop there in the latest installment of her career revival.

"It's wonderful to start the year out with this appearance," said Williams, who hadn't reached the semi-finals in Australia since 2003, the year she lost the final to her sister, Serena. "I want to go further. I'm not happy just with this. But I'm so happy to be in the position to like go further."

Williams didn't reach the quarter-finals at any of the Grand Slams from 2011 — when she was diagnosed with the Sjogren Sydnrome, which saps energy and causes joint pain — and the 2015 Australian Open.

She lost in the first round here last year, but returned to reach the semi-finals at Wimbledon and finished the year ranked 17th. Vandeweghe also lost in the first round here last year, and at the US Open last September, but has hit form in Melbourne. As well as the wins over Kerber and Muguruza, she has had wins over No. 15-seeded Roberta Vinci and Eugenie Bouchard, who reached the semi-finals here and the final at Wimbledon in 2014.

Williams said the quarter-final results were a "great win for the US"

"I'm sure she's going to want to be in her first final," Williams said. "I'm going to want to be in only my second final here. So it's going to be a well-contested match."

Williams dropped four service games against Pavlyuchenkova, but she responded each time by breaking back. In the tiebreaker, she trailed 3-1 before winning the last six points — clinching the match on Pavlyuchenkova's double-fault.

It earned her a spot in the semi-finals for the second time in three majors — after a six-year absence from the last four.

With her run to the Wimbledon semi-finals last year, Williams became the oldest woman since Martina Navratilova (at 37 years, 258 days) in 1994 to advance so far at a major.

With Serena Williams in the quarter-finals and targeting a record 23rd major, there's the prospect of another sisters final in Australia.

Williams isn't looking across the net, though, saying that's not what makes a champion. She is focused on Grand Slam title No. 8.

"I try to believe," she said. "I'd like to be a champion, in particular this year. The mentality I walk on court with is: 'I deserve this'."