German Sabine Lisicki fired the fastest serve ever recorded at a WTA event on Tuesday, unleashing a 210.8 kph (131 mph) bomb in her first round loss to Ana Ivanovic at the Stanford Classic.
Lisicki, who lost 7-6(2) 6-1, unleashed the serve in the opening set of their match on the plexipave hardcourt surface at Stanford University. She won the point despite former world number one Ivanovic getting her racket to the ball.
The WTA said the serve bettered the previous record of 207.6 kph set by American Venus Williams at the US Open in 2007.
"Well ... at least I broke the world record for fastest serve on @WTA ...," Lisicki tweeted after her defeat.
Defending champion Dominika Cibulkova was another first round loser in Stanford on Tuesday, going down 6-2 4-6 6-2 to 20-year-old Spaniard Garbine Muguruza.
The fastest serve ever recorded on approved equipment in professional tennis was the 263.4 kph (163.7 mph) rocket hit by Australian Sam Groth at an ATP Challenger event in Busan, South Korea in May 2012. He too lost the match.