Miami - Simona Halep missed the chance to return to world No 1 as a devastating display from Karolina Pliskova sealed the Czech's passage into the Miami Open WTA final 7-5, 6-1.
Romania's Halep would have reclaimed the top spot in women's tennis if she had reached Saturday's showpiece following current No 1 Naomi Osaka's early exit and Petra Kvitova falling to Ashleigh Barty in the last eight.
But Pliskova, the world number seven, had other ideas, rattling off an incredible nine games in a row to blitz Halep and set up an intriguing battle with Australian Barty - a 6-3, 6-3 winner over Estonian Anett Kontaveit.
"It wasn't easy waiting for so long but I managed to stay aggressive," said Pliskova, who hit 29 winners to Halep's 18 in the match that finished after 1 am thanks to a series of rain delays. "Ashleigh is a good player, but I am excited for the final.
The South Florida weather played havoc with Thursday's schedule at Hard Rock Stadium, no more so than when the rains returned with Pliskova on the brink of a brilliant win.
Play was initially halted at 3-3 in the in the first.
When they resumed, Halep edged ahead 5-3 before Pliskova roared back, taking the first set and a 5-0 lead in the second before rain forced them from the court again.
Halep, who recovered from 1-5 down in the second set in her quarter-final match against Wang Qiang, held serve upon the restart.
But in the very next game, Pliskova served out to ruin Halep's hope of reclaiming the number one ranking she lost when Japan's Osaka won the Australian Open earlier this year.
Results on Thursday from the WTA and ATP Miami Open hardcourt tournament (x denotes seeds):
Men
Quarter-finals
Roger Federer (SUI x4) bt Kevin Anderson (RSA x6) 6-0, 6-4
Denis Shapovalov (CAN x20) bt Frances Tiafoe (USA x28) 6-7 (5/7), 6-4, 6-2
Women
Semi-finals
Ashleigh Barty (AUS x12) bt Anett Kontaveit (EST x21) 6-3, 6-3
Karolina Pliskova (CZE x5) bt Simona Halep (ROM x2) 7-5, 6-1
