Probably demonstrated superior stamina as he saw off favourite Cristoforo Colombo in the Dubai Duty Free Full Of Surprises Railway Stakes at the Curragh.
David Wachman's runner (7-1) was dropping back in distance by a furlong for the Group Two contest after winning over seven furlongs at Limerick last time out and the extra touch of staying power proved crucial in the closing stages.
Joseph O'Brien produced 11-10 favourite Cristoforo Colombo to win his race inside the distance, but Probably was far from finished and responded gamely as Billy Lee asked him for another effort, and he prevailed from the market leader, with Tiger Stripes third.
Wachman said: "He showed us plenty right from the start. He's a very good looking horse, plenty of size and scope and we always liked him. He ran well here the first day and won a maiden in Limerick beating a horse that subsequently won, so we were expecting him to run well.
"As a three-year-old he'll definitely be better. He's a big horse and we'll run him in some of the better races in the autumn and we'll see how we get on.
"He's a very good actioned horse and he'll definitely prefer better ground, but he stayed well today and Billy gave him a good ride. He's a very good rider, Billy Lee, very underrated."
Rawaaq made an impressive start for Dermot Weld as she claimed the Dubai Duty Free Voyager EBF Maiden. Partnered by Pat Smullen, Rawaaq was sent off an unconsidered 20-1 shot for the six-furlong heat, but she flew inside the distance to land the prize.
Leitir Mor, who finished seventh in the Coventry Stakes at Royal Ascot, looked to have the race in the bag as he took over from the prominent favourite George Vancouver, but he had to settle for second, two and a half lengths behind the winner. George Vancouver lost third to stablemate Afonso De Sousa.
Weld said: "I think they went very fast early on. Pat was wise to take his time. She came home nicely and she handled the conditions. We'll leave her off now and go for a Group race in August.
"She's a filly we've always liked, but we were concerned beforehand about her handling the ground as she has shown a lot of pace."