Colin Montgomerie celebrated his 43rd birthday by claiming a two-stroke lead at the halfway stage of the Johnnie Walker Championship.
A second five-under-par 68 for a total of 10-under-par 136 gave the Scot an advantage over former winner and compatriot Paul Casey (71).
Sweden's Robert Karlsson (68), Dane Soren Hansen (70), Marcus Fraser of Australia (68) and Britain's Andrew Marshall (67) are a further stroke behind, but overnight leader Thomas Bjorn slipped four shots off the pace after a 75.
Stephen Browne remains best of the Irish on 4-under-par. Browne was just three shots off the lead yesterday, but two bogeys, couple with three birdies meant he was unable to improve his position.
Despite hauling himself to the top of the leaderboard, Montgomerie, who was presented with a birthday cake with after his round, had another mishap on a finishing hole.
On Sunday, he lost the US Open by double-bogeying the 18th at Winged Foot and in the first round at Gleneagles he bogeyed the last to miss out on a share of second place overnight.
This time, he missed a three-foot birdie putt to deny himself a larger leading margin. Having gained his final green in two at the par-five finish, Montgomerie three-putted from 20 feet.
'I just don't know what's going on here,' said a perplexed Montgomerie after signing for a round that contained six birdies and one bogey.
'That's my third round in a row and that's not good at all. If I can't two-putt from 20 feet there's something wrong. There was nothing difficult about it at all.'
