Poulter began the third round two shots behind Padraig Harrington, but birdied his opening hole and then broke out of a four-player logjam with consecutive birdies on Nos. 7 and 8. At 9 under, he holds a three-shot advantage over Harrington and Patrick Reed.
Only 51 minutes of third-round play were completed Saturday before heavy storms dropped nearly five inches of rain at PGA National. Players returned to the course at 10 a.m. ET Sunday, and third-round play concluded at 4 p.m.
The fourth round began at 2:40 p.m., as players were not re-paired in an effort to complete as much golf as possible before sunset, which is estimated at 6:21 p.m. The group of Poulter, Harrington and Reed began the final round at 4:30 p.m.
"I don't know how far we're going to get right now," Poulter said in between rounds. "Every hole today was crucial, and every hole that we're going to go and play right now will be as well."
Poulter has a pair of PGA Tour wins to his credit, but he remains in search of his first stroke-play title on U.S. soil. His prior two victories came at the 2010 WGC-Cadillac Match Play Championship and the 2012 WGC-HSBC Champions, which was played in China.
While conditions have been difficult for much of the week at PGA National – only 10 players were under par through 54 holes – Poulter has played his last 36 holes in 10 under, making only a single bogey.
Among the players chasing Poulter on the Champion Course is Phil Mickelson, who began the final round tied for fifth at 3 under, six shots back. Mickelson carded a 1-under 69 in the third round and is in search of just his second top-10 finish on Tour since the start of the 2013-14 season.