Nahaarr had finished ninth when favourite for the Stewards' Cup at Glorious Goodwood
Nahaarr landed a gamble to win the Ayr Gold Cup having been backed down to be 7-2 favourite.
The four-year-old, ridden by Tom Marquand for Newmarket trainer William Haggas, had been more than double the price on Saturday morning.
He came with a late surge to deny 22-1 chance Spanish City, with Mr Lupton in third and Soldier's Minute fourth.
"It was an exceptional turn of foot," said Marquand who won the St Leger last Saturday on Galileo Chrome.
The jockey, who had never ridden a winner at Ayr, completed a 51-1 treble with victory on Johan after the earlier success of Addeybb.
"It's been a good day," said Haggas, who watched the race on television at home.
"We had 15 seconds in about a week and six of those were beaten a short head, so we deserved a bit of luck and thankfully we've got it today."
