The big-hitting 31-year-old, known as one of the more outlandish and uppity characters on the tour, scored his third successive 66 by keeping his head while all about him were far from steady. Sandelin, once reported by Phil Mickelson for his machine-gunning gestures with a putter, still sports a 52-inch driver and often wears bright-green crocodile-skin shoes. For the third round he wore a shirt with a collar so wide it resembled a small tent.
If this was an anti-choking device, it worked. Sandelin overtook Paul Lawrie after the Scot threw away his fine start of three birdies in his first six holes. But after a bogey on the next hole, Lawrie was plugged in sand at the 376-yard eighth and needed three attempts to get out.
The hole cost him a triple-bogey seven and, by following that with a bogey six on the long 10th, Lawrie, winner of the Qatar Masters by seven shots in February, fell five behind. Despite a birdie at the short 11th, he ended the day seven shots off the pace.
The Dubliner Paul McGinley matched Sandelin's 66 and moved into second place on his own on the 15-under-par mark of 201. The 32-year-old is coached by Pete Cowen, with whom Darren Clarke parted company earlier this week.
A bogey at the long 12th, where he had to chip out left-handed from beside a tree, set him back, but three birdies in the next four holes revived hopes of only a third European tour victory for the Irishman.
Among those five shots adrift is Kent's Jamie Spence, furious with himself for dropping two shots in the last three holes. However, thanks to an eagle at the 507-yard 12th, he still has realistic hopes of a first victory since the 1992 European Masters in Switzerland, where he fired a tour record 60 in the last round.
Earlier, 19-year-old Sergio Garcia's professional debut continued with a 70, which left him at six under. A top 10 finish, which would get him into next week's Italian Open, is still on. Every peseta Garcia earns is of importance as he is allowed only seven starts on the tour this season and needs to win around pounds 55,000 to avoid the dreaded tour qualifying school in November.