Scott Hend saw his lead cut to two shots as the final round of the weather-affected Omega European Masters got under way at Crans-sur-Sierre Golf Club.
The Australian had to complete five holes of round three in the morning after a lengthy fog delay on Saturday and picked up a shot to get to 12 under as he looks to make up for last season's play-off defeat in the mountains.
A bogey on the third saw him drop back to 11 under when the fourth round got under way, leaving him two ahead of England's Matthew Fitzpatrick and Paraguayan Fabrizio Zanotti.
Swede Alexander Björk, Kiwi Ryan Fox, England's Tyrrell Hatton, American Daniel Im and South African Richard Sterne were then at eight under.
Fitzpatrick had dropped a shot in his three remaining holes first thing but hit a smart approach to the second to record a birdie and get back to nine under.
Playing partner Hatton also birdied the second with Sterne birdieing the third to edge up the leaderboard.
Hend then dropped a shot after finding sand off the tee on the par three third with Zanotti parring all three of his opening holes.
Im started the round nine shots off the lead but turned in 32 from the tenth and added gains on the first and second to surge through the field.
Fox began his round with a bogey but quickly got back on track with gains on the fourth, fifth and seventh, while Björk was level par for his first three holes.
There was then a group of ten players four shots off the lead including defending champion Alex Noren, who had completed eight holes.