Keothavong was impressive and can now chase a first WTA Tour win
Anne Keothavong became the first British woman since 1983 to reach the semi-finals of a WTA Tour clay-court event by winning in Warsaw.
Keothavong crushed Ioana Raluca Olaru 6-0 6-1 and will meet Maria Sharapova's conqueror, Alona Bondarenko.
"I think I can be really proud that I've reached the semis on clay, which is my least favourite surface," said the 25-year-old Londoner.
"I'm finding my form and I'm getting used to competing at this level."
Keothavong was far too proficient to give her inexperienced opponent any realistic chance.
In a match lasting just 70 minutes, the British number one converted five of the eight break points she was presented with by a nervous Olaru, the 20-year-old who had beaten Jelena Dokic in the first round.
Keothavong won the first 11 games, but Raluca Olaru just avoided the double bagel.
"I played well but I think that my opponent was probably a bit tired," said Keothavong.
"She'd come through qualies and she had a lot of tennis coming into the match."
Keothavong's feat comes 26 years after Shelly Walpole reached the semi-finals of the Swedish Open and Jo Durie made the last four of the French Open, both in 1983.
Her win will almost certainly put her back into the top 50 and, having made two previous WTA semi-finals this year, the 25-year-old from east London will now be bidding to make her first final.
"It would mean an awful lot to get to a first final after getting to the semis a few times, and it would mean even more because it's on clay," she added.
"I expect Friday to be tough though. I played Bondarenko before a couple of years ago and lost to her and she's been playing pretty well lately.
"She's just come off beating a former world number one and a Grand Slam champion and she'll be very tough to beat."
Keothavong and South on the French Open
Bondarenko, seeded eight, played some excellent tennis to see off her celebrated Russian opponent and end the former world number one's involvement in her comeback tournament.
Sharapova, 22, was beaten 6-2 6-2 in what was her first WTA event in nine and a half months following a shoulder injury and subsequent surgery which had seen her drop to 126 in the rankings.
Bondarenko, 24, is one of only two seeds left in the tournament. The other, Daniela Hantuchova, is in the opposite half of the draw.
Sharapova, a three-time Grand Slam-winner, was broken early in the first set by Bondarenko, who looked sharper and moved much more easily around the court.
The Ukraine player broke again to love in the seventh game before serving out to take the set in 35 minutes.
Bondarenko, the world number 39, wasted no time in the second set, breaking Sharapova in her first service game and taking full advantage of the errors creeping into the Russian's game to break again twice for a 5-0 lead.
Sharapova, who had won a tough first match in Warsaw before cruising through round two, eventually rallied to pick up two games before Bondarenko served out for the match.
In the opposite half of the draw, Alexandra Dulgheru of Romania beat Kazakhstan's Galina Voskoboeva 6-1 7-5 and will face Hantuchova, a 6-3 4-6 6-4 winner in her quarter-final against Klara Zakopalova of the Czech Republic.
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