Wimbledon champion Venus Williams powered into the Japan Open semi-finals with a 7-6 6-3 win over Australia's Alicia Molik on Thursday.
Williams's superior athleticism gave her the first set tiebreak 7-4 and the top seed was never seriously troubled in the second, closing out the match in one hour, 33 minutes.
The American former world number one, who claimed last week's Korean Open title, has now won 18 of 20 matches since winning her sixth grand slam singles title at Wimbledon.
Williams will face unseeded Caroline Wozniacki in the last four in Tokyo after the Dane's 6-3 2-6 7-6 win over Czech Klara Zakopalova.
In the $832,000 men's event, big-serving Croatian Ivo Karlovic scraped past Asia's number one Lee Hyung-taik in 7-6 6-7 7-6 in an epic struggle lasting two hours, 38 minutes.
Seventh seed Karlovic will next play either former world number one Lleyton Hewitt or Spain's Ivan Navarro.
Spaniard Fernando Verdasco, the eighth seed, battled past former Australian Open champion Thomas Johansson of Sweden 7-6 5-7 6-3 to book his place in the quarter-finals.