What it means: McIlroy stayed in the driver's seat to win the season-long Race to Dubai title, and now after a 7-under 65 he has a great shot at closing the season with his fourth win of the year. But he'll have to get past Sullivan, who is also seeking his fourth title of a breakout year.
Round of the day: McIlroy started hot with three birdies in his first four holes, and he rebounded from his lone bogey on No. 12 with birdies on 13, 14 and 15. However he failed to record his ninth birdie of the day when he missed a short putt on the par-5 18th.
Best of the rest: Coming off a T-3 at the BMW Masters, An shot a 6-under 66 to move into fourth place and four behind Sullivan. An won at Wentworth earlier this season, and also added a win in Korea in September. And while Grillo only managed a 1-under 71, he closed with four straight birdies to finish four off the lead and gave himself a shot on Sunday to win on the Web.com Tour, PGA Tour and European Tour in a span of six weeks.
Biggest disappointment: Justin Rose started the day at 7 under par and had a great chance to put himself in position for his third win of the season, but he struggled all day and tumbled down the leaderboard after signing for a 6-over 78.
Storyline entering the final round: While McIlroy may consider 2015 a 'lost' season with no major wins and an ankle injury, he can certainly close in style and walk away with two trophies – one for winning the DP World Tour Championship and one for winning the Race to Dubai. But keep an eye on Reed. He's been on fire since heading overseas with top-10s in Hong Kong, the CIMB, WGC-HSBC Champions and BMW Masters.