World champion Ronnie O'Sullivan was forced to dig deep to establish a slender one-frame advantage over Ricky Walden after the first session of today's Roewe Shanghai Masters final.
The Rocket could not shake off his determined opponent, a qualifier from Flintshire making his first appearance in a ranking final, as he eased into a surprise 3-1 lead.
But the world number one hit back at the Grand Stage, winning four of the next five frames to edge ahead in the Far East.
O'Sullivan is bidding to become the first professional player for 15 years to win three consecutive ranking titles.
Only Scotland's Stephen Hendry, Welshman Ray Reardon and fellow Englishman Steve Davis have ever achieved the feat.
The Chigwell cueman won the Northern Ireland Trophy, the first ranking event of the season, in August, which followed his World Championship triumph in May.
However, although Walden has much less experience than O'Sullivan having only played in a handful of finals since he turned professional in 2000, the world number 35 was not overawed by the occasion.
And it was the 25-year-old, who upset Masters champion Mark Selby in the semi-finals with a 6-4 win yesterday, who was the better starter.
O'Sullivan pinched the opening frame with runs of 48 and 39, but Walden won the next three to deservedly lead at the mid-session interval.
A break of 47 helped level matters, before impressive breaks of 74 and 94 gave the former Young Player of Distinction a two-frame advantage.
But O'Sullivan raised his game following the resumption and quickly restored parity. A break of 58 reduced his arrears to 3-2, before runs of 64 and 31 levelled matters.
The triple Crucible winner won the next frame with a break of 87, before Walden pocketed a composed run of 56 to make it 4-4.
However, it was O'Sullivan who gave himself the lead ahead of tonight's concluding sessions (12.45pm Irish time) thanks to a break of 78 in the ninth and final frame.
If O'Sullivan, appearing in his 31st ranking final, were to win the tournament it would be his 22nd ranking title. He has won two titles in a season eight times in his career so far.
But if Walden upsets the form book and beats the favourite, he would become the 16th player from outside the top 32 to win a ranking event and put himself on the verge of a top-16 place in the latest provisional rankings.