Svetlana Kuznetsova held off a strong challenge from Switzerland's Timea Bacsinszky in searing afternoon heat to book her place in the Miami Open final with a 7-5 6-3 victory.
The 15th-seeded Russian relied on a never-say-die attitude and a powerful baseline game as she improved her career record to 3-0 against the Swiss, ending the match with a crunching backhand crosscourt winner after nearly two hours on court.
Kuznetsova, who won the Miami title in 2006, will next meet either Victoria Azarenka of Belarus or second seed Angelique Kerber of Germany who were scheduled to play their semifinal later on Friday at Crandon Park.
"I am happy that I could hang in there and never let my hands down," Kuznetsova told ESPN in a courtside interview.
"I have not been feeling my best but I have been fighting every ball and just trying to run as much as I could.
"I was praying to finish it in two sets so I can have a little bit of time to rest," smiled the Russian, referring to Sunday's final.
"I really tried to enjoy the match, even though I couldn't feel my best shots. I had to fight. This is what tennis is about."
Kuznetsova, who pulled off a stunning upset when she ousted world number one Serena Williams in the fourth round, won a hard-fought opening set after ending a brilliant baseline slugfest between the two with an overhead smash.
Though she failed to hold serve in the first game of the second set, the Russian broke her 19th-seeded opponent in the second and fourth games to lead 3-1, then fought back from 15-40 down on serve in the ninth to seal victory.
Bacsinszky, who beat third-seeded world number two Agnieszka Radwanska of Poland in the fourth round, converted just two of 14 breakpoint opportunities during the match.