The defection of a promising rival has opened the door for consistent mare Lady Echelon to post her first win in open company at Eagle Farm on Saturday.

Trainer Matt Dunn has decided to run rising star Buakaw in the AON Human Resources Plate over 1400m in preference to the 1600m of the Premier Fire Open.

"He would have got close to 59kgs in the open after they rehandicapped it, so I went for the easier option," Dunn said.

Dunn's decision not to accept with Buakaw has left the Natalie McCall-trained Lady Echelon with five rivals in the 1600 metre race.

McCall has always been frank in her opinion that Lady Echelon is a handy mare on dry tracks but a very good one in the wet.

"We will run her Saturday and then hopefully in a feature race in a fortnight," McCall said.

"We will pick and choose our races from there.

"There are plenty of races for her during the winter such as the Glenlogan Park Stakes, Gai Waterhouse Stakes et cetera but I think only on wet tracks as I don't think she would be up to the good ones on the dry."

Lady Echelon has won five races including the Listed Fillies and Mares Tatts Classic but is yet to win in open company.

Meanwhile, Lady Echelon's well-performed stablemate River Lad is set to trial next week before returning to racing in the weight-for-age Victory Stakes at Eagle Farm on April 19.

River Lad showed he could compete with the best sprinters in Australia with a last-start second to star mare Appearance in the Expressway Stakes at Randwick on February 8.

McCall is aiming River Lad at the major winter carnival sprints including the Group One Stradbroke Handicap on June 8.