MARC Warren agonisingly let a last-16 spot slip from his grasp as he suffered a heartbreaking extra-hole defeat to Brooks Koepka on the second day of the WGC-Cadillac Championship at Harding Park in San Francisco.
The Scot lost the last three holes, missing from three feet at the 18th for the win, before succumbing to a birdie-2 from his American opponent at the 20th.
It meant that Warren, who’d beaten J B Holmes by 2&1 in his opening match on Thursday, went from being in the driving seat to progress from the group to playing a dead rubber against Russell Henley in his last round-robin match on Friday.
Even if he wins that and Koepka loses to Holmes, the American will go through as the head-to-head results will be used as tie-breakers.
Warren, making his debut in the £6 million event, looked set to follow up his splendid win over Holmes when he birdied the 15th to go three up on Koepka only to lose the 16 and 17th to pars then the 18th to a birdie.
He had putts at each of them to close the door and probably faced a sleepless night over the three-footer he failed to convert at the last.
In fairness to Koepka, he’d got up and down from a greenside bunker there to make his birdie and almost holed it for an eagle.
He repeated the feat to stay alive as the 19th was halved in birdies before hitting a superb approach to around three feet at the next to clinch an unlikely victory.
Warren had laid the foundations for getting the upper hand by holing a ten-foot birdie putt at the par-5 first before the American, a winner in Phoenix this year and also a winner in Turkey at the end of last season, followed him in from six feet for a half.
Both players then missed the green at the second - a 200-yard par-3 - but, for Koepka, that led to a double-bogey and Warren, who made 4 from a greenside bunker, had his nose in front.
He quickly went two up when Koepka, after finding sand with his approach, made another double-bogey at the third, but a hole-winning birdie at the next for the American from nine feet was more like him.
Warren’s second birdie of the day at a par-5 - from feet at the 606-yard fifth - took him two up again only for Koepka, the 2013 Scottish Hydro Challenge winner, to hit back once again by taking the seventh with a par-4.
The ding-dong battle continued when Warren birdied the eighth from six feet to give himself a cushion once more and, on this occasion, it led to him going three up as a tap-in par proved good enough to win the ninth as well.
Big-hitter Koepka drove the green at the 336-yard 12th to win it with a birdie-3 only for Warren to seem to dampen his opponent’s enthusiasm for a late fightback by rolling in an 11-footer at the 15th for his fourth birdie of the day.
Unfortunately for the Scot, his putter then deserted him when he needed it most and Koepka ultimately made him pay a costly price.
Stephen Gallacher suffered a second straight defeat after he squandered a two-hole lead at the turn in losing 3&2 to Matt Kuchar, a former winner along with the Scot’s first-day conqueror, Hunter Mahan.