Istabraq could not manage an emotional fourth Champion Hurdle as Hors La Loi III won Tuesday's showpiece race.

Istabraq was pulled up after just two flights of hurdles and second favourite Valiramix, partnered by Tony McCoy, had to be put down after suffering a serious leg injury.

In the absence of its chief rivals, Hors La Loi stormed home to win by three lengths from second-placed Marble Arch and Bilbao in third.

I just felt I might have done damage if I went on Istabraq jockey Charlie Swan

In a dramatic start to the Smurfit Champion Hurdle Challenge Trophy, Istabraq seemed to hurt his back after jumping the first.

He stiffened up, obliging jockey Charlie Swan to swiftly call it a day.

Valiramix roared into contention along with the likes of Mr Cool, Ansar, Geos and Landing Light.

But the grey gelding clipped heels with Ansar and fell.

Valiramix was taken off the track by horse ambulance and sedated but eventually had to be put down.

Hors La Loi, partnered by Dean Gallagher, took the lead and held off Marble Arch and Bilboa.

Istabraq was not heavily backed right up until the 11th hour when a flood of bets - possibly inspired by the early Irish successes - put him up to favourite.

Istabraq seemed to hurt his back at the first

But it was 10-1 chance Hors La Loi - second behind Istabraq two years ago - who became the new name on the trophy.

Gallagher said: "I can't believe it. It's a dream that has become reality and I'm absolutely overwhelmed."

The jockey admitted that he heard Istabraq's retirement announced on the loudspeakers at Cheltenham.

He said: "I thought 'That's one out of the way'."

Swan, who was competing in his 11th Champion Hurdle, said he felt all was not well with Istabraq at the first fence.

"His action went after the first hurdle," said Swan.

"I just felt I might have done damage if I went on. I am glad I pulled him up. I am obviously disappointed as he is such a good horse."

When Swan pulled the bay gelding up, thousands of fans burst into a round of applause to salute the horse's achievements.