The Leicester cueman is finding form at just the right time as he prepares for his World Championship title defence at the Crucible later this month and victory on Sunday would give him a fourth ranking triumph of the season.
Selby had his work cut out to shake off a determined Kyren Wilson in his semi-final, with his opponent making a superb break of 130 in the sixth frame to level the match at 3-3.
The next two frames were shared before Selby went on to seal a 6-4 win, making a 93 break in the 10th.
Earlier Welsh veteran Williams saw off Hossein Vafaei 6-1 in a one-sided semi-final.
The Welshman raced into a 5-0 lead against Vafaei, who had beaten Judd Trump earlier in the week to guarantee his best ever ranking return.
Vafaei's 98 break saw him edge frame six but Williams, who had registered the only century of the match in frame four, closed with a 69 to cruise into the final.
He's now one win away from a return to the World Championship, 14 years on from the second of his two victories in the event.
"I’ve been practicing quite a bit lately. I know about the incentive that if I win the tournament, I qualify for the Crucible, but I haven’t won in a while," said Williams.
"At the start of the week it was five or six games to qualify for the Crucible and looked out of my reach. Now it’s only one match, it’s within my grasp now really.
"I’m not anxious or nervous, I’m just excited. I’ve won this tournament a few times before and this is one of my favourite places to come and play."
China Open: Final day schedule
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Sunday April 2
Afternoon Session (0700 GMT)
Final, first session (Best of 19 frames)
TV Coverage: Eurosport 1/Quest
Mark Williams v Mark Selby
Evening Session (1230 BST)
Final, second session (Best of 19 frames)
TV Coverage: Eurosport 1/Quest
Mark Williams v Mark Selby
