Frenchman Jo-Wilfried Tsonga survived a test to beat Latvia's Ernests Gulbis 4-6 6-4 6-3 and advance to the Japan Tennis Open semi-finals.
The world number seven ended the qualifier's resistance by pounding down his 19th ace of the match after a questionable line call had gifted him triple break point in the deciding set.
Tsonga will play fellow Frenchman Gael Monfils next after the fourth seed battled past Switzerland's Stanislas Wawrinka 2-6 6-3 6-4 in the late quarter-final.
Earlier, Russia's Mikhail Youzhny knocked out defending Tokyo champion Tomas Berdych with a 6-2 7-6 victory.
Youzhny faces former world number one Lleyton Hewitt in Saturday's semi-finals after the Australian pulverised Frenchman Edouard Roger-Vasselin 6-4 6-0 in the day's first match.