Poulter played bogey-free in the rain-delayed third round for a 4-under 66 to take a three-shot lead over Padraig Harrington and Patrick Reed. It was the first 54-hole lead for Poulter on the PGA Tour.
But he hit a shank into the water and made double bogey on the par-3 fifth hole, and then hooked his tee shot into the water for a bogey.
Patrick Reed had the lead with a long birdie off the green at No. 5, only to give it back with a bogey on the par-3 seventh. Casey, meanwhile, went out in 31 and was tied with Poulter at 7-under par.
The final round resumes at 8 a.m. Monday.
