Jim Furyk roared to the top of the leaderboard at the halfway point of the Nedbank Challenge, leaving Padraig Harrington et al in his wake after firing a six-under-par 66 at the stormy Sun City course.
The American took full advantage of an early slip from first-round leader Henrik Stenson and a second straight bogey-free round moved him to 10-under overall, four shots clear of the second-placed Swede.
Even a thunderstorm, which saw play suspended for two-and-a-half hours with five holes remaining for the leading pair, failed to break Furyk's rhythm.
Stenson, who led his playing partner by one overnight after opening with a flawless 67, could only manage a 71 after virtually cancelling out today's three birdies with two bogeys.
That left him on six-under, one ahead of Ernie Els and Charl Schwartzel.
European Order of Merit winner Harrison held a share of third until a final-hole bogey saw him drop to a tie for fifth.
After a level-par first round, Els flew up the leaderboard with a 67, largely thanks to a front-nine 32.
Schwartzel followed up yesterday's 70 with a 69, despite once again carding birdies and bogeys in almost equal measure.
Things went from bad to worse, meanwhile, for Colin Montgomerie.
Bottom of the leaderboard after a first-round 75, he made a quintuple bogey after hitting the trees three times at the par-four 11th.
Only a marvellous eagle at the last spared him a 79 but he is still eight over going into round three.
A determined Furyk did not take long to make his move today, helped by some wayward early drives from Stenson.
He turned the one-shot deficit into a one-shot lead after the Swede bogeyed the second and he himself birdied the third.
Further birdies followed at the seventh and ninth, after Stenson had birdied the sixth to get back to level par for the round.
Furyk tightened his grip by picking up shots at 11 and 13 before the storm came.
A brilliant bunker escape on the resumption of play then handed him his final birdie at 14, where Stenson also picked up one of his two back-nine birdies.
