Davy Bonilla settled his mount at the rear as John Gosden's Centennial set the pace.

Though Shemima looked threatening a furlong out, Watar swooped late for a five-length victory.

"It was an impressive performance, but he may have been a little flattered as it was a small field and everything went right for us," said Head.

"We'll see how he comes out of this, but I see no reason why not to look at the Prix Royal-Oak.

"I hope he can develop into a Cup horse next season."

John Gosden had to settle for third in the opening stayers' event with Centennial and a similar fate befell him in the Qatar Prix de Royallieu with Dar Re Mi.

The filly - sent off a short-priced favourite - had finished second to the Arc favourite Zarkava at the track almost three weeks ago, and struck for home once in the straight.

Having travelled powerfully she appeared to have made a race-winning move before Andre Fabre's Balladeuse and La Boum swept down her outside to fill the first two places.

Winning rider Olivier Peslier said: "She accelerated very well having been tapped for speed on the descent.

"While some of the others got bumped coming through the field she got a clear run down the outside, and is an improving filly."

Richard Hannon's Paco Boy ran out an easy winner of the Group One Prix de la Foret.

Settled at the rear by Christophe Soumillon as Duff set a brisk pace up front, his supporters were never anxious.

Natagora moved up menacingly a furlong out but once Soumillon, riding him for the first time, asked Paco Boy to quicken the response was immediate.

Hannon's son and assistant Richard jnr said: "He loved that ground today and he's always been a trier.

"I thought he'd gone in his coat but he's done it very well."

Soumillon said: "I must thank Richard Hughes because he gave me good instructions on how to ride the horse. I hope he has the same feeling at Newmarket on Darjina later."

Hannon jnr continued: "He's unbeaten over seven furlongs and now he's won a Group One that takes care of his stallion career and we can look at other things.

"He deserved a Group One and while he was beaten fair and square here last time, he was a little keen and didn't have much room in the closing stages.

"The Breeders' Cup Mile is an option, the owners are keen but he might have done enough for this season.

"Seven furlongs is obviously his trip but he has limited options over that distance.

"I think he does stay a mile which means we can look at the likes of the Lockinge and QEII next year."

The official distance was three lengths.

Aidan O'Brien's Yeats was surprisingly beaten at odds-on for the second successive year in the Prix du Cadran as Bannaby sprung a surprise under Soumillon.

Trained in Spain by Mauricio Delcher Sanchez, who saddled Equiano to King's Stand glory at Royal Ascot, the five-year-old just held off Incanto Dream in a desperate finish.

Johnny Murtagh was sending out distress signals early in the straight on the triple Ascot Gold Cup winner and he failed to pick up, trailing home in fifth.

Murtagh said of Yeats: "He just ran badly."

Delcher Sanchez said of the winner: "It's fantastic to win two Group Ones this season over distances ranging from five furlongs to two and a half miles.

"He'll stay in training next year and will be aimed at the Gold Cup."

Olivier Peslier gave Spirito Del Vento a great ride to win the Prix Daniel Wildenstein for the second successive year.

Dermot Weld's Famous Name attempted to make all and set a frantic early pace with Sageburg sat in his slipstream.

Soumillon looked confident on Sageburg as he pulled out to challenge but Peslier timed his run to perfection on Jean-Marie Beguigne's five-year-old.