Darren Weir has claimed his third successive South Australian Derby win with Leicester giving Melbourne's premier trainer his ninth Group One win for the season.

Ridden in a prominent position by Damian Lane, Leicester, the $4 favourite, took the lead at the 300m and kept the advantage to hold off the fast-finishing Rezealient ($21) by 1-1/2 lengths.

VRC St Leger winner Runaway took the minor placing another half length away after setting the tempo.

It was the second successive Classic win for Weir after Sopressa took out last Saturday's Australasian Oaks at Morphettville.

Weir praised Lane's ride, saying he positioned him perfectly to get the gruelling 2500 metres.

"I was a bit umming and aahing what to do and was told to get in front of a fair few and lob in the box seat and that's what Damian did," Weir said.

"The run that he had, he needed that run to show that turn of foot.

"Had he had a tough run I doubt he would have been able to run the trip but the way that Damian rode him was perfect.

"He switched him off and got him into the right spot and more importantly didn't press the button until the last 200 metres."

Lane said he was aware of the concerns about the distance.

"The genuine tempo really helps this horse. There were concerns about the trip but he put that to bed," he said.

"It's a great day for me and he presented in great order today."

Weir's previous wins in the SA Derby were Howard Be Thy Name (2016) and Volatile Mix last year.

His other runners on Saturday, Savaheat and Civil Disobedience, finished 12th and 15th respectively in the 16-horse field.