US Open 2017: Coco Vandeweghe beats Karolina Pliskova to make semi-finals
|Venue: Flushing Meadows, New York Dates: 28 Aug-10 Sept|
|BBC coverage: Live radio and text commentary on selected matches every day.|
Coco Vandeweghe ended Karolina Pliskova's reign as world number one as she reached the US Open semi-finals with a straight-set win.
The 20th seed won 7-6 (7-4) 6-3 in the last eight at Flushing Meadows.
Vandeweghe, 25, goes on to face compatriot Madison Keys in the last four in New York.
Keys' victory over Kaia Kanepi ensured the first all-American semi-final line-up at the US Open since 1981 with Venus Williams facing Sloane Stephens.
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"I watched the match last night with Venus," said Vandeweghe.
"She said it best, we have to admire Serena. They all inspire me to be the next best American."
Pliskova, 25, needed to reach the final to hang on to the number one ranking, but defeat means she will be replaced by Spain's Garbine Muguruza in the new standings next week.
"I mean, I don't care," she said afterwards.
"I don't think something is going to change if you are number two. Like, I don't see any difference between this. So for me, no changes."
'I always dreamed of being on the main stage'
Vandeweghe had said beforehand that it would be a match of "first-strike" tennis between two of the best servers and biggest hitters in the game, and the American proved the more clinical.
She won 56% of the rallies under four strokes, which accounted for the vast majority as both women looked to back up heavy serves with quick winners.
Vandeweghe capitalised on a poor service game from Pliskova with a fizzing forehand return to break for 2-1, but her early calm ended abruptly in game eight.
Two double faults in succession prompted an angry racquet smash from the American and moments later Pliskova swung a forehand winner into the corner to break back.
There were signs that the Vandeweghe backhand was beginning to falter but another heavy forehand return gave her a break at the start of the tie-break, and she served it out clinically from there.
Pliskova had come into the match with a tournament-leading 31 aces, but the Czech would add only two more as she struggled to establish control.
Vandeweghe got the better of three successive breaks in the second set and, urged on by coach Pat Cash in the stands, served her way to victory in one hour and 35 minutes.
"Even though we're out here individually, it's really a team sport," Vandeweghe told the crowd. "The team work as hard as I do.
"When I won this event as junior at 16 I always dreamed of being on the main stage. It is a process and here I am. I couldn't wish for anything better."