Johnson, a SC native, shot a three-under 68 in trying conditions to end on 10-under 203, making his move with three consecutive birdies from the 13th and holding on to his lead despite dropping shots at 16 and 17.
Shane Lowry held on to his slender lead at the RBC Heritage on Friday though the Irishman still has two holes left to complete his second round after play was suspended for the day at the weather-hit SC tournament.
It left Lowry, in the penultimate group, needing to hole his second shot from 180 yards at the 460-yard par four 18th to tie, but he finished with a par.
"It's something when I was younger I always dreamed of", Pan told CBS. "That's a big key around here". "The wind blew consistently all day". "The course played very hard, especially the last three holes with the wind direction we had", Johnson said. "It was hard to make putts". The overall highlight came when Johnson dropped a massive 47- foot putts.
"It would be special", Johnson said.
Lowry had held the overnight lead despite being one of a number of players who had not finished their second round before bad weather struck in SC on Friday. But a bogey on the par-3 17th following a tee shot into the bunker ruined his chances of a second tartan jacket.
He counted himself lucky to escape with a bogey four. "And holed out with a four and obviously that was huge", said Lowry, who went on to record his third bogey of the back nine on the 16th.
"That was a really nice save", Johnson said. He finished it proving that not even the world's best golfer is immune from occasionally looking like just another Sunday afternoon hacker.
Poulter got off to a awful start but was faultless the rest of the way. 11-13 and double bogeys on Nos. Made it tough. But I hit a lot of really solid golf shots.