The Irish trio of Graeme McDowell, Shane Lowry and Rory McIlroy remain in contention but it was Brandt Snedeker who stole the show with a sensational second round 60 at the RBC Canadian Open in Hamilton Golf Club in Ontario.
The 38-year American registered a flawless 10-under-par 60, which included eight birdies and an eagle at the fourth, to surge into tied second with Canada's Nick Taylor.
Had Snedeker holed out on the 18th fairway, he'd have joined Jim Furyk as only the second player to have carded two sub-60 rounds on the PGA Tour.
The Tennessee native carded a 59 in the first round of the 2018 Wyndham Championship last August, remarkably doing so after bogeying the opening hole. Alas, in Ontario he would have to make do with a birdie on the last for a round of 60.
A mediocre opening round of 69 means that Snedeker is not even in the lead, trailing joint-leaders Scott Brown and Matt Kuchar, both have registered seven under par rounds of 63 on Friday.
Shane Lowry led the Irish charge but a sloppy finish saw him drop a couple of strokes to fall back to tied-7th on eight under par at the end of Friday.
A smooth front nine had seen Lowry roll in three birdies and then a superb eagle on the par-5 fourth (his 13th) saw him climb to -11.
However, that was the cue for a costly series of holes, Lowry registering a bogey, a double-bogey and a bogey between the 5th and the 8th.
He recovered some of the damage with a birdie on his final hole to leave himself four shots adrift of the leading pair.
Joining him on eight under par is McDowell, who at one stage led the tournament by two strokes after getting to nine under par early in his inward nine. However, bogeys on the 4th and 7th (he started on the back nine) saw him fall back to eight under par.
McDowell, who is from Portrush, is not currently exempt for the British Open which will be played at Royal Portrush next month.
The top three finishers in the Canadian Open who are not already exempt for the British Open - provided they are within the top-10 finishers at the Canadian Open - will earn exemptions for the British Open.
Rory McIlroy is one shot further back on seven under par after carding a second round 66. The Holywood golfer opened his second round with a bogey but responded with a trio of birdies from the fifth as he moved into the red numbers.
Further birdies at the 11th and 17th improved his score to eight under but a bogey at the last recorded his second blemish of his round. He sits one shot clear of Thursday night leader Keegan Bradley who slumped to a disappointing 71.
The remaining two Irish players, Seamus Power and Padraig Harrington, failed to find their form and fell the wrong side of the two under par cut line.
Power carded a second successive 70 to remain at even par while Harrington registered a two over par round of 72 to miss the cut by five strokes.