Trainer Aidan O'Brien could have four runners in Sunday's Prix de l'Arc de Triomphe at Longchamp after deciding to pay a late entry for English St Leger winner Leading Light.

The Montjeu colt has displayed versatility this year, winning twice over a mile and a quarter (2000m) before stepping up to two miles to take the Queen's Vase at Royal Ascot.

He came back to a mile and three-quarters to claim Classic glory at Doncaster earlier this month and will now pit his wits against the world's top mile-and-a-half performers in France.

Epsom Derby winner Ruler Of The World, Camelot and Kingsbarns are the other potential Ballydoyle representatives in the Arc.

"The four (Arc) horses are Ruler Of The World, Leading Light, Camelot and Kingsbarns," O'Brien told At The Races.

"I think we're going to supplement the Leger horse and then obviously we'll get closer to the weekend (before knowing) about ground (conditions) because Camelot would only run if it was good or better.

"He (Leading Light) obviously hasn't done a lot (since Doncaster) - it's not that long ago - but everything he's done we've been happy with."

Roger Charlton's Al Kazeem also remains on target for Europe's premier middle-distance prize after pleasing in a workout with Prix de l'Opera-bound stable companion Thistle Bird over the weekend.

"They both worked well on Saturday morning over eight furlongs on our summer gallops, which are in fantastic condition," the trainer said on his website.

"Although Al Kazeem has had some tough races and on ground faster than he would have preferred, from what I can see he still retains his enthusiasm and his speed figures compared well on Saturday morning with his work before both the Prince of Wales's Stakes and the Eclipse.

"There is no disputing that this year's race is going to be contested by the best horses in Europe and two very smart colts from Japan.

"We will need all the assistance we can get in Europe's most exciting race but some ease in the ground and going right handed will help him."