Heather Watson is top Briton
Heather Watson has become British number one for the first time in her career.
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The 20-year-old replaced Anne Keothavong as Britain's leading player when the new WTA ranking list was published on Monday.
In reaching the second round of the singles at last week's Bank of the West Classic in Stanford, Watson moved up from 79th to 71st in the world rankings.
Keothavong, who lost in the first round of the same tournament, slips from 75th to 76th.
For the first time since 1991, Great Britain now has four players ranked in the top 100 after Laura Robson moved to a career-high of 91st following her impressive run to the semi-finals of the Italiacom Open in Palermo.
Elena Baltacha - British number one during the first half of the season - is now only the fourth ranked player in her country. She is now at 100th on the WTA list.
Watson, who also won the doubles tilte in Stanford, and Keothavong both play at this week's Mercury Insurance Open in Carlsbad, California, so the situation could change again.
Meanwhile, Robson continues to play on the European clay at the Sony Swedish Open in Bastad. She faces a tough opener though, meeting third seed Anabel Medina Garrigues.