Keothavong is making her first appearance in the main draw

Britain's number one beat the Spaniard, 132 places above her in the world rankings, 6-1 7-5 7-6 (7/4) in a match lasting two hours 40 minutes.

But Monday's action was overshadowed by a serious-looking injury to French number five Marion Bartoli.

She was taken to hospital in great pain with a suspected broken hip after slipping on the grass.

Earlier, Jane O'Donoghue was the first British casualty at Edgbaston as she lost 6-4 7-5 to France's Emilie Loit.

She was followed out of the tournament by Elena Baltacha, who went down 6-3 6-2 to qualifier Samantha Stosur of Australia.

Magui Serna of Spain was the biggest name to fall so far on the opening day of the tournament.

The number 12 seed lost her first-ever meeting with Luxembourg's Anne Kremer 6-2 6-2.