Danny O'Brien may have found himself a Derby contender in the spring after Grinzinger Bishop produced a stunning form turnaround at Flemington.

Long-priced winners are rare for the O'Brien stable but, even so, Grinzinger Bishop's knockout win at $71 at Flemington on Saturday did not come as a shock for connections.

O'Brien, who also won the opening Flemington event with stayer Saracen Knight on Saturday, explained after Grinzinger Bishop's boilover win that the two-year-old son of Almanzor had trialed well before a moderate debut where he struggled on a very wet surface at Geelong.

"He went to Geelong with some expectation - he's a horse that's always trialed well and he's a horse that's always impressed us," O'Brien said.

"The Geelong track was really wet, he got back on that Soft track and basically barrier-trialed, he was rolling in his box the next morning.

"We put a set of blinkers on him on Tuesday morning, really the only hope of getting a half decent surface was to run him in town. I spoke to (owner) John (Wheeler) earlier in the week and said 'We're going to run him, we think he's a lot better than what he did at Geelong'."

O'Brien's longest-priced city winner since 2007 had been Douro Valley's $41 upset in the Caulfield Stakes in 2008 and Shamrocker was at $31 when she won the 2011 Australian Guineas.

Starting at $71 and paying $95.60 for a $1 win bet on the Victorian TAB, Grinzinger Bishop had a three-quarter-of-a-length margin on the line over Magnaspin ($10) with half a length to Zoe's Promise ($31) in third place.

Beau Mertens rode Grinzinger Bishop and he explained later that O'Brien had filled him with some confidence as he legged him aboard.

"Danny informed me he's not here for no reason, he just went around at Geelong, Heavy track, inexperience," he said.

"He seemed to take a lot from that run because he jumped really well, put himself into the race and travelled really kindly for me."

A $55,000 yearling buy from Karaka, Grinzinger Bishop may swiftly go from an unwanted winner over winter to a Victoria Derby hopeful, according to O'Brien.

"He's a horse we're hoping might be a Derby horse in the spring - he stayed on there super today," he said.

Story by Andrew Eddy for Racing.com

Pic by Racing Photos