Champion steeplechaser Mazzacano may have run his last race with trainer Robbie Laing baffled by his performance at Sandown on Saturday.Laing said he would have exhaustive tests carried out on Mazzacano who ran one of the worst races of his life in the Australian Steeplechase.Shooting for what would have been an history-making third victory in the 3900 metre event, Mazzacano was sent out favourite but his rider Steven Pateman eased him out of the race when he was struggling back in last place.L

Champion steeplechaser Mazzacano may have run his last race with trainer Robbie Laing baffled by his performance at Sandown on Saturday.

Laing said he would have exhaustive tests carried out on Mazzacano who ran one of the worst races of his life in the Australian Steeplechase.

Shooting for what would have been an history-making third victory in the 3900 metre event, Mazzacano was sent out favourite but his rider Steven Pateman eased him out of the race when he was struggling back in last place.

Laing couldn't find anything wrong with Mazzacano who has won eight of his 12 jumps starts.

"He's not trying because I think he's looking after something which may be about to go," Laing said.

"He may have had a bleed internally, I don't know.

"He ran about four seconds quicker than the hurdle when he won in April but yesterday he couldn't beat time with a stick.

"We'll do exhaustive tests on him, we'll scan him, have his heart and lungs checked and if we find something that's serious, we'll retire him. He's done his job, he's been a great horse.

"He's overcome a lot of injuries. He's had bowed tendons and ruptured tendons, three on one front leg and two on the other."

Laing said when vets scanned Mazzacano's leg after he ruptured a tendon during his win in the 2007 Crisp Steeple at Sandown, "they couldn't find any tendon".

Mazzacano is raced by Greg Mance, the owner of Saturday's Sandown 2400 metre winner Oak Heart.

A rising 10-year-old by Sir Ivor, Mazzacano has raced 49 times overall for 11 wins, 10 placings and has earned more than $350,000 prize money.

Meanwhile Laing is looking forward to switching his Australian Hurdle trio to steeplechasing after they were comprehensively beaten by the outstanding Black And Bent who has now won six straight on the flat and over the jumps.

Corries ($26) ran on well to be runner-up, albeit 12 lengths astern of Black And Bent, with Vindicating 1-3/4 lengths away third.

Last year's Grand National Hurdle winner Desert Master ($7.50) swapped the lead several times with Black And Bent before weakening to finish fifth of the seven runners.

"My three are going to make very good steeplechasers," Laing said.