New Zealand three-year-old El Roca has been confirmed as a starter in the Doncaster Mile with Glen Boss booked to ride.

El Roca ran a solid third in Saturday's George Ryder Stakes (1500m) behind Gordon Lord Byron and Speediness after leading from the barriers.

Co-trainer Trent Busuttin said he was not sure El Roca was a genuine 1600m horse but the temptation to go to the Doncaster on a light weight was a deciding factor.

Doncaster weights will rise at least 1.5kg in the absence of the topweight It's A Dundeel, meaning El Roca will carry 51.5kg and possibly more if Boban and Gordon Lord Byron bypass the race.

The other option for El Roca was the TJ Smith over 1200m.

"I'm not sure if he really gets the mile but you don't get many chances to get into a Doncaster on this weight," Busuttin said.

"I was really proud of him in the George Ryder and it would be nice to get him into a race where he could be ridden a little quieter."

El Roca has had four starts so far in his Sydney campaign, beating Dissident to win the Eskimo Prince Stakes (1200m) first-up on February 15.

His momentum was halted when he was taken out of the Hobartville Stakes won by Dissident two weeks later after he was given a normal treatment the day before the race, against the rules.

He ran second to Terravista in the Liverpool City Cup (1300m)before going back to his own age group in the Randwick Guineas (1600m).

After being hampered early on, he missed a Group One win by just a short head when second to Dissident.

"He's not far off winning a big race," Busuttin said.

"He just hasn't been able to get one yet."

El Roca is now the TAB's $8 second favourite for the $3 million Doncaster on April 12 behind Messene at $3.20.