Former top-ranked player Judd Trump was beaten by Jack Lisowski in the first round, reports Xinhua.
The 30-year-old Englishman shot a 3-1 lead with a break of 91 in the first frame before interval. Walden fought back one frame but couldn't find his pace anymore.
"I didn't play as well (as yesterday)," said Selby, who missed the final victory in International Championship, The Masters and the PTC Finals this season.
"Obviously, I'm happy (to go back to No.1), but the main thing is to still be in and win this tournament and then lead it to the World Championships."
Mark Selby is slated to meet Mark Williams next Friday. Williams fought back three straight frames from 2-4 to capture victory against Allister Carter at 5-4.
--IANS (Posted on 28-03-2013)