In this May 1, 2017 photo, England's Mark Selby plays a shot during the World Championship Snooker final match against Scotland's John Higgins at The Crucible in Sheffield, England. (PAUL ELLIS / AFP)

LONDON - World number four Mark Selby swept Chinese teenager Fan Zhengyi 4-0 to reach the second round at the Snooker English Open on Monday.

World champion Ronnie O'Sullivan, played his match in Milton Keynes, England with pink nails in an effort to raise awareness for breast cancer research

Selby, having won the European Masters last month, is one step closer to defend his English Open title and will meet another Chinese player Chang Bingyu in the last 64.

The 18-year-old Chang defeated Irish teenager Aaron Hill 4-2 in the first round.

China's top player Ding Junhui came from 3-0 down to beat compatriot Si Jiahui 4-3 while world champion Ronnie O'Sullivan also fought back from 2-0 down to knock out Frenchman Brian Ochoiski, 4-2.

O'Sullivan, 44, played his match in Milton Keynes, England on Monday with pink nails in an effort to raise awareness for breast cancer research.

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"It's good to get behind great causes and great charities," O'Sullivan told the World Snooker Tour website. "It's something I have never been involved with before, but I thought it was a great idea. If it helps create awareness for breast cancer that can only be a positive thing."

Ahead of the start of the first round, player Stuart Carrington and referee Andrew Barklam tested positive for COVID-19.

Carrington came into contact with Sam Craigie on Sunday, so both players have been withdrawn from the event.

Thepchaiya Un-Nooh and Anthony McGill both received a bye to the second round.