Tony Finau birdied his last three holes in the third round to take a three-shot lead into the final day of the WGC-HSBC Champions.
The American started Saturday with that advantage before defending champion Justin Rose reeled him in and moved two ahead with two to play on a dramatic day at Sheshan International Golf Club.
But while Finau completed his big finish to get to 13 under, Englishman Rose dropped three shots on the final two holes to sit three off the lead alongside American duo Patrick Reed and Xander Schauffele.
Reigning Race to Dubai champion Tommy Fleetwood was then five shots off the lead alongside America's Andrew Putnam.
Finau's round of 70 put him in pole position to claim his first European Tour win at just the 20th attempt but the chasing pack have plenty to play for in Shanghai.
A win for Rose could move him back to the top of the Official World Golf Ranking, while a Reed victory could put him top of the Race to Dubai Rankings presented by Rolex.
Fleetwood could also move to the top of the Race to Dubai standings, while Schauffele and Putnam are both still seeking their first European Tour wins.
"I'm looking forward to tomorrow," said Finau. "I've got a world-class field chasing after me. This is the position you want to be in and I'll be looking to close out my first tournament in this position, which is exciting for me. Whether it happens or not, it's an experience that you learn from and you continue to move forward.
"It was great to birdie the last three. It's always a nice way to finish no matter what position you're in. I didn't have a lot going my way for the first half of the day and Rosey was making his run. I was just really pleased I was able to finish that way and get some momentum going into tomorrow."
Finau, Reed and Rose all birdied the par five second - with Reed bouncing back from a bogey on the first.
This is the position you want to be in - Tony Finau
The leader missed the green and played a poor chip on the third and with European Tour Affiliate Member Schauffele birdieing the second, third and fifth, he was just one shot back.
A Schauffele double-bogey on the next meant the lead was briefly back to two before there was a two-shot swing in the final group. Rose holed an 18-footer on the fifth to get into double-figures and heap the pressure on Finau, with the man from Utah missing a short one to leave himself in a share of the lead.
A stunning approach into the seventh moved Rose into top spot on his own and when he hold a 12-footer on the par five eighth, he was two ahead. He gave the shot back on the next after finding sand off the tee but holed a 15-footer on the 13th to once again move two in front.
Reed also bogeyed the ninth but played an exquisite pitch on the tenth and he birdied the 13th and 14th to get back to ten under alongside Finau - who bogeyed the 12th but bounced back on the 13th.
A bogey on the 15th saw Reed drop back alongside Schauffele who had bounced back well from his double with birdies on the seventh and 14th and a bogey on the ninth.
Schauffele holed a huge putt on the 16th to get to double-figures but that was three back when Rose almost drove the same hole and got up and down for a birdie, with Finau and Reed also picking up shots on the short par four.
Finau almost made a hole-in-one on the 17th and the birdie was enough to give him the lead after Rose found the hazard off the tee and surrendered a double-bogey.
Reed found the same hazard but got up and down to drop just a single shot, with he and Finau taking advantage of the par five last while Rose found the water to make a bogey.
Fleetwood had been one off the lead after birdieing the third, fourth and tenth and dropping a shot on the fifth, but he triple-bogeyed the 14th after finding the water before picking a shot back up on the last.
Putnam made one bogey in a 67 to sit a shot ahead of Thai Kiradech Aphibarnrat and fellow American Keegan Bradley, who both fired rounds of 70.
Jason Day was at six under, a shot clear of Thorbjørn Olesen, Patrick Cantlay and Billy Horschel.