Brave Watson lets the lead slip after heat takes its toll

(Getty Images)

Heather Watson's hopes of a third WTA quarter-final of the year ended with a three-set defeat by Canada's Stéphanie Dubois at the Citi Open in Maryland on Thursday.

The British No 3 looked on course for victory when she led by a set and a break but, with temperatures soaring, she could not close it out. Dubois saved nine of 10 break points in a tight second set before dominating the decider to win 3-6, 7-5, 6-1.

Watson is ranked 13 places higher than Dubois, at 104 in the world. The 19-year-old from Guernsey had won their only previous meeting 6-1, 6-0 earlier this year and took five straight games on her way to securing the opening set. But Dubois, 24, held on gamely in a tense second set before reeling off six games in a row from 5-5 as she went on to win in a gruelling two hours and 40 minutes, which included a break before the decider under the extreme heat rule.

Dubois said after her win: "I never gave up. She was playing well. I stayed aggressive and I managed to play more aggressively in the second set. She is consistent so I knew I had to make something."