Stewards have opened an inquiry into the defeat of a beaten favourite at Canterbury, saying they are worried about betting trends on the race.

In-form stayer Mr Steal eased from $3.20 to $4.20 before finishing third in the TAB.com.au Handicap.

Ridden by Hugh Bowman, Mr Steal settled outside the leader Springbok Flyer and looked certain to miss a place before getting his second wind.

He finished almost five lengths from the winner Springbok Flyer.

Mr Steal went into the race as an all-the-way winner over 1900m and last-start runner-up at Randwick when beaten in a photo finish.

After asking trainer Bjorn Baker why Mr Steal didn't lead, stewards said betting patterns on Wednesday's event needed further examination.

"I have to say the betting is a little concern," acting chief steward Marc Van Gestel told Baker.

"The horse has traded quite widely on the (betting) exchange."

Baker told the inquiry he thought Mr Steal might have been vulnerable over the extended distance and was reluctant to tell Bowman to take up the running.

"I wish I did say lead at all costs but I had it in my mind that it was 2700 metres," Baker said.

Baker said he thought Mr Steal would run well after finding form at his past two starts.

"I even made him Bjorn's Best on Twitter this morning and that has a very good record for my followers," he said.

The inquiry has been adjourned to allow stewards to further analyse betting sheets.