The Chris Waller-trained winner Reliable Man has upset triple crown-winning colt It’s A Dundeel in the $500,000 Queen Elizabeth Stakes at Randwick on Saturday.

But in a concerning postscript to the Group One, the French Derby winner had to be led back to the saddling enclosure without jockey Hugh Bowman.

The entire was put into a horse ambulance in what chief steward Ray Murrihy said was a precautionary measure.

Asked if he knew what happened to his mount, Bowman said: “I’ve got no idea, but he is clearly lame.”

Reliable Man was having his second Australian start under the care of Waller, who 24 hours earlier avoided a penalty over a spate of positive swabs in his stable.

An inquiry found that a contaminated batch of feed led to three Waller-trained horses testing positive.

“The last 24 hours have obviously been tough, but I haven’t looked forward to a day’s racing as much as today,” Waller said.

Given a perfect run by Bowman, Reliable Man shot to the front at the 200m and he had 2-1/2 lengths in hand at the finish over It’s A Dundeel.

As is customary, It’s A Dundeel settled last and he made his run four wide on the bend, but was unable to bridge the gap on the winner.

South Australian galloper Happy Trials finished third.