Fergal Lynch brought Jamesie with a telling late run to land the Gulf News Tabloid (Handicap) at Meydan as trainer David Marnane kept up his fine record at the Dubai Carnival.
Merhee looked like justifying 4-1 favouritism for Mike de Kock when holding a handy lead going into the final furlong, but Lynch had other ideas on Marnane's charge.
Benefiting from his encouraging run over seven furlongs on this course two weeks earlier, the Irish raider was not inconvenienced by the drop to six furlongs and took command close home.
A model of consistency, Jamesie was scoring for the first time since winning at Fairyhouse in July 2011, after which he had been second no less than seven times including at Royal Ascot.
Marnane said: "It's great and no more than he deserved. He's been knocking on the door in these big handicaps over the years.
"He loves that surface and we'll probably run him back in three weeks' time in the Group Three sprint, again over six. He quickened well today.
"It's a step up (in class), but he loves the Tapeta and he will get better."
Certerach (10-1) gave Irish trainers a quick double when striking for Michael Halford in the GN Focus Handicap on turf.
Shane Foley drove the six-year-old through a gap to hit the front inside the final furlong to head Tanfeeth and hold the late-finishing Topclas by half a length.
Although without a win since October 2012, Certerach ran with credit in three races at the Dubai Carnival last year.
Frankie Dettori was out of luck on his first ride at the Carnival following his fairytale return from injury at Lingfield on Wednesday, where he recorded a double.
He drove his Norwegian-trained mount Silver Ocean to vie for the lead with Not A Given after two furlongs, only to weaken quickly in the straight in the Gulf News Classifieds Handicap.
Victory went to the De Kock-trained Alexandra Palace (7-1) under Christophe Soumillon. Free Wheeling, ridden by Silvestre de Sousa for Saeed bin Suroor, was second.
After his victory, Certerach is set to run in the two races over a mile and three-quarters he was placed in last winter.
"We were thrilled with him. It was great on his first run back out here," said Halford.
"He's in good form and we'll bring him back here in a fortnight's time. There's a handicap here for him on February 6 over 14 furlongs.
"If all goes well he'll come back on March 8 for a Group Three, so it's the same plan as last year."
Windhoek, having his first start for Godolphin and trainer Saeed bin Suroor, just held Layali Al Andalus in a driving finish to the XPRESS Handicap.
The 3-1 joint-favourite, formerly with Mark Johnston, prevailed by a neck in the hands of De Sousa. Mutajare was third.
Windhoek was once seen as a possible Derby contender last year, but after winning his first three starts, he was only fifth behind Libertarian in the Dante Stakes at York and was then beaten in four subsequent races.
Soumillon denied Dettori victory in the feature Group Two Al Fahidi Fort Sponsored by Gulf News when scoring on Anaerobio.
The De Kock-trained seven-year-old got first run on Mshawish, ridden by Dettori, after Pearl Flute had led into the final furlong.
Mshawish finished with a flourish but could not get past his fellow 5-1 joint-favourite. Pearl Flute hung on for third in the seven-furlong contest.
Soumillon said: "His form last time was quite good, but he's quite a difficult ride in a morning so it was difficult to say how much he had improved.
"When I asked him to quicken he went straight away."