Sabine Lisicki hits fastest serve in women's tennis

Germany's Sabine Lisicki hit the fastest-recorded serve in the history of women's tennis at 131mph during a first-round loss in Stanford, USA.

The 2013 Wimbledon finalist hit the serve in the 11th game of the first set against Ana Ivanovic, who would go on to win the match 7-6 (7-2) 6-1.

Venus Williams had set the previous record of 129mph at the 2007 US Open.

Australian still holds all-time record

The fastest recorded serve in professional tennis was 163.4mph by Australian Sam Groth at a Challenger event in South Korea in 2012. The ATP does not officially recognise service speed records "because of the variance in radar guns", but confirmed at the time that the Busan event used approved equipment.

"Well at least I broke the world record for fastest serve," Lisicki said on Twitter  after Tuesday's match.

In Washington, British number one Heather Watson suffered a first-round exit at the Citi Open.

The 22-year-old from Guernsey lost 6-3 1-6 7-6 (7-3) to Belgian Kirsten Flipkens, ranked nine places higher at 47 in the world.

Watson, who has risen from 113 in the world at the start of the year, won the doubles title in Baku last week but since Wimbledon has lost in the first round of singles in both Baku and Washington.