British number one Anne Keothavong squandered an apparent match-winning position as she lost seven games out of eight to go down to former Wimbledon runner-up Marion Bartoli in the Bank of the West Classic.

The world number 82 was 4-1 up in the deciding set and seemingly on her way to a third-round meeting with world number eight Anna Chakvetadze when she lost four consecutive games to hand her French opponent the initiative.

Although she levelled at 5-5, Keothavong was powerless to stop Bartoli who closed out a 6-3 1-6 7-5 victory.

Bartoli, the world number 15, had raced through the first set after taking a 3-0 and 4-1 lead.

However, the second set was an entirely different matter with Keothavong in complete control.

After both women held serve for 1-1, the Briton won five successive games to level the match at one set all.

Bartoli held serve to go 1-0 up in the decider but Keothavong won the next three games to appear on course for another highly-impressive victory following her defeat of world number 33 Sania Mirza in the first round.

However, Bartoli produced an excellent fightback to take a 5-4 lead forcing her opponent to serve to stay in the match.

Keothavong managed to level but the relief was merely temporary as Bartoli went on to take the next two games and move into round three.