Mark Foster leads the way at a fog-delayed Johnnie Walker Championship at Gleneagles, after a six-under-par 66.
The Englishman holds a one-stroke advantage over Spaniard Ignacio Garrido and Argentina's Tano Goya but many players failed to complete 18 holes.
Scotland's James Byrne was three under par with nine holes still to play due to the delayed start.
Former Ryder Cup captain Colin Montgomerie finished on one under having played 16 holes.
A swarm of wasps also caused problems, with several players ducking and swatting their way around the course.
"We were backing off nearly every shot," said Foster. "I had to make a 12-to-15 foot birdie putt with a wasp on me.
"I'm pleased with the way I scored because I've only played once in the last six weeks and I felt under-golfed."
Foster, a former English amateur champion, was back playing with his Walker Cup partner David Howell and hit four birdies on the front nine, but there were two bogeys that kept his lead over Garrido down to a single stroke.
His round came after he warmed up no fewer than three times because of the morning fog.
None of the delays affected him as badly when he ended up three clear and then lost by one after missing three-foot putts on the 16th and 18th.
Among the later starters were Montgomerie and Jose Maria Olazabal, who were one under and one over respectively with two to play.
Defending champion Edoardo Molinari was another to finish in twilight, the Italian trailing eight shots off the lead after a 74.
Earlier in the day Liverpool's Nick Dougherty was two under after three and joint leader, but his horror run of missed cuts going back to last November looks set to reach 21 after he fell away to a 76.
Dougherty, a member of the last three Seve Trophy sides who has slumped from 46th in the world three years ago to 773rd, ran up a quadruple-bogey seven on the short sixth and was six over before closing with an eagle that does at least give him some hope of surviving to the weekend.