Colin Keane celebrates his treble at Naas© Photo Healy Racing
Mustajeer kept on best in the mile and a quarter handicap at Naas to give trainer Ger Lyons and jockey Colin Keane a treble on the card.
Keane's title chasing rival Pat Smullen had sent Espoir D'soleil to the front over a furlong out but Mustajeer had her well within his sights.
The 11/4 favourite motored up on the outside to head her at the furlong pole. Espoir D'soleil rallied on the inner but in the final 100 yards Mustajeer forged on to score by three and a quarter lengths.
Espoir D'soleil had to settle for second at 9/2. Fiesole (8/1) came in third, a further half a length back.
Ger Lyons said: "Coming here I thought this was my best chance judged on everything we were seeing at home.
“We knew he wanted further and we knew he'd handle the ground. He looked around a good bit when he hit the front so you'd like to think there is a little bit of improvement in him.
“I think there is another day for him either in Leopardstown or back here. We can step up to twelve (furlongs) if we want to but today was important and it's a good day in the office for everybody concerned. I'm delighted.”
This was Mustajeer's first start for Ger Lyons having formerly been with Owen Burrows in Lambourn.
Lyons and Keane also enjoyed victories with Moonlight Bay (9/2) and Elegant Pose (9/4f) today. The treble paid just over 66/1.
Keane moved seven clear of Smullen in the race for the Irish Flat Jockeys Championship in riding his 90th winner of the campaign.
Paddy Power slashed Keane from 2/9, before racing today, to 1/20 to claim his first title while they pushed Smullen out to 8/1 from 100/30 before racing today.
Additional reporting by Gary Carson