LONDON, June 12 (Reuters) - American teenager Iva Jovic earned her first career victory against a top-five ranked opponent as she battled past compatriot Amanda Anisimova to reach the semi-finals of the Queen's Club Championships on Friday.
The 18-year-old produced a fearless display on the slick grasscourt to beat the second seed 6-2 3-6 6-3.
Top seed and world number two Elena Rybakina also bowed out as she lost 7-5 2-6 6-4 to British wildcard Katie Boulter.
Both Rybakina and Boulter were playing their second matches of the day as organisers played catch-up after rain washed out the entire programme on the Thursday.
Former Wimbledon champion Rybakina had not hit a ball in anger all week after receiving a bye in the first round.
Earlier in the day she had come within two points of being sliced out of the tournament by defending champion Tatjana Maria, eventually finding her range to win 6-7(4) 7-5 6-0.
Mother of two Maria, 38, defused Rybakina's power game with her unique blend of under-cut forehands and backhands -- the ball skidding low on the turf.
But once Rybakina managed to cut out the unforced errors there was only one outcome likely in the decider.
Rybakina also battled back from losing the first set against Boulter late in the evening on the Andy Murray Arena and looked favourite to reach the semi-finals in the decider.
But Boulter produced some aggressive tennis to stay in touch and then broke Rybakina's serve in the ninth game before serving out an impressive victory and setting up a semi-final against Croatia's lucky loser from qualifying Donna Vekic.
It was the biggest win of Boulter's career by ranking.
Vekic, ranked 76th, also had a busy day, first beating Czech Marie Bouzkova 7-6(9) 6-3 and then returning to beat another Czech, former world number one Karolina Pliskova 6-4 4-6 6-3.
Jovic will face either Briton's Emma Raducanu, who beat Romania's seventh seed Sorana Cirstea 6-4 6-2, or Uzbekistan's Kamilla Rakhimova who outlasted British wildcard Harriet Dart.
Raducanu's match against Rakhimova was held over to Saturday after light ran out on a marathon day at the London venue.
Jovic had never won a WTA main draw match on grass until this week but is proving a fast learner.
"Every match I feel more confident on the grass," Jovic, ranked 19th in the world, said. "I have to keep working on my serve, my return -- the first couple of shots in the point are super important on grass.
"But it's trending in the right direction. Just stacking up the matches."
Last year's Wimbledon runner-up Anisimova had the edge in power, striking 29 winners but Jovic resisted and made only 15 unforced errors in the match to the 39 from Anisimova.
Having taken the first set, sixth seed Jovic went 5-0 down in the second but managed to regain some momentum heading into the decider and grabbed an early service break.
Anisimova threw everything at the teenager in a bid to salvage the situation but Jovic held firm to reach her fourth semi-final in a breakthrough year.
(Reporting by Martyn Herman; Editing by Hugh Lawson and Pritha Sarkar)
