Simona Halep reached the Wuhan Open quarter-finals on Wednesday despite being knocked dizzy and forced to retire from a doubles match a day earlier.

The Romanian world number five beat Yaroslava Shvedova 6-3, 6-3 before detailing the heavy blow from a ball which left her with bruising to her head.

Halep was struck by a shot fired from the baseline by her doubles partner Jelena Ostapenko, before retiring from the match on Tuesday evening.

"She hit me with the ball, like 150 kilometres (90 miles) per hour. I was dizzy in the first moment, but then was much better," Halep said. 

"I feel pain all around here, but it's okay," she added, gesturing to the left side of her head.

Halep said she was cleared by doctors to play, and will meet American number nine Madison Keys in the quarter-finals on Thursday.

The Women's Tennis Association doesn't have the concussion protocols adopted by other sports to ensure players have fully recovered from blows to the head.

Concussions in tennis are rare -- but they do happen, as when China's Li Na was briefly knocked out in a fall during an Australian Open final in 2013.

Canada's Eugenie Bouchard cut short her season last year with concussion problems after she slipped and fell in the locker room during the US Open.

Former world number one Victoria Azarenka bowed out of the 2010 US Open after what was described as a "mild concussion" when she tripped getting off a treadmill. 

She lasted about half-an-hour into her next match before collapsing on court and being taken off in a wheelchair.

Meanwhile, Australian doubles player Casey Dellacqua sustained a career-ending concussion at the China Open in 2015, retiring in May this year.

Head injuries are an increasingly hot issue in sport, prompting a raft of rule changes in rugby union, rugby league and American football. 

Source: AFP