Simon Foster says racing experience is his main motivation in backing up Diamond Princess in the Perth Racing #Ascothappens Plate (1100m) on Saturday.

Foster admitted he flirted with the idea of resting Diamond Princess but elected to press ahead with the Oratorio filly despite her torrid run at Ascot last week.

Diamond Princess found herself trapped three and four wide for the majority of the trip and had every reason to pack the race in after such a tough run.

But she refused to yield ground and determinedly closed the race out running the second quickest 600m when fourth, beaten 2 ½ lengths, behind The Celt.

Foster has a big opinion of the $17,000 yearling who was in search of her second win after scoring on debut at Bunbury on New Year’s Day.

“She still does things wrong and is green but shows a lot of potential,” said Foster.

“Last week she probably should have rolled forward, but I’m teaching her to settle.

“It’s not my nature to back them up but she is one tough filly.

“If she had drawn wide I wouldn’t have started her.

“From her gate she can go forward and be put into the race.

“Even at Bunbury she raced wide throughout.

“I want to see be put into the field.

“She needs that experience before the Magic Millions.”

Foster will get a good measure on how strong is Diamond Princess’ potential when she takes on raging $1.85 favourite, The River.

The Magnus colt earned his position at the head of the market after posting one of the best two-year-old wins of the season last month.

On debut at Ascot he looked ultra-impressive after coming from the back and reeling in the leaders with a strong closing finish.

He is one of two runners for Trevor Andrews with stable mate Trademark, also in with solid claims and on the third line of betting.

The Trade Fair gelding is $5.50 on the strength of his one length second to Swedish Memories when first-up last December.

In a field of eight starters The River has drawn barrier seven for Shaun McGruddy, while Paul Harvey, who partners Trademark for the first time, starts from gate four.

Jerry Noske retains the mount on Diamond Princess and starts from gate three. The daughter of Oratorio is rated a $7.50 chance.

RWWA: Julio Santarelli