Scotland's Stephen Gallacher and Denmark's Thomas Bjorn shared the halfway lead at the Omega European Masters, while Padraig Harrington played himself into contention.
Gallacher recorded seven birdies in his second round of 65 but a bogey at the 394-yard 18th meant he surrendered the outright position at the top of the leaderboard.
Bjorn, the 2011 champion at Crans-sur-Sierre, also came unstuck at the last and had to settle for six birdies in his 66, which was good enough to lift him to 10 under.
The pair led the chasing group of Englishmen Danny Willett, Richard Finch and Tommy Fleetwood, France's Victor Dubuisson and 2010 winner Miguel Angel Jimenez by one stroke.
A further shot back were the likes of first-round leader Anirban Lahiri, who managed only a level-par 71, and Paul Casey, with a 69, while three-time major winner Harrington's 65 sent him soaring into contention at seven under.
Elsewhere, Gareth Maybin is on three under after a 69, while Michael Hoey is two under after a 71.
Of the other Irish involved - Simon Thornton, Darren Clarke, Damien McGrane and Peter Lawrie missed the cut.
Gallacher has been struggling recently with a back injury and will take some time off after this week but it did not hamper him too much in the Swiss mountains.
"That was a solid round again today," he told europeantour.com. "I hit the ball really well on the front nine and got my just rewards for the putts and I'm still in there for tomorrow.
"Experience always seems to come through on this course and that's what I'm hoping for at the weekend" - Thomas Bjorn
"My back has been a bit sore but I've had a lot of physio and it has settled right down. I am having a break after this week to get it properly right."
Bjorn credited a break of a different kind for putting him in contention.
"I've been struggling technically and there have been some big changes this week because I found myself very poor technically over the last few weeks," said the Dane.
"I've gone back to doing it myself and sometimes that's the best way.
"Experience always seems to come through on this course and that's what I'm hoping for at the weekend.
"But you can't get carried away on this golf course or you will run up big numbers."
Having been through a serious slump - dropping to 169th in the world rankings after a snowboarding accident - Casey has re-emerged as a force on tour this season and having broken back into the world's top 100 he has his sights set on making the top 50 to ensure his entry to next year's majors.
"Winning is the biggest goal, getting back in the top 50 is the other biggest - everything else takes care of itself," he said.
"There are lots of other goals but it is about continuing to keep playing solidly and give myself opportunities to win tournaments and try to close them out.
"You have to have a lot of patience and creativity this week. If you are not willing to risk something you are probably not going to get it close.
"You don't need to do a lot wrong to struggle round this place but I'm still happy to shoot two under par as it still keeps me in the mix."