Dwayne Dunn will be the new rider for Mossin' Around when she contests a mares' race at Caulfield.

Dunn rode a treble at Caulfield last Saturday and sits on top of the Melbourne premiership early in the season.

Trainer Grahame Begg has decided to drop Mossin' Around back to a benchmark 90 race over 1100m on Saturday following an interrupted program.

Mossin' Around jarred up when at the tail of the field in the Cockram Stakes at Caulfield last month before missing a race when the Sandown meeting was called off after three races on September 7.

A planned Mornington jump-out last week, which was transferred to Pakenham and then eventually abandoned, prompted Begg send the mare to Cranbourne for a 800m barrier trial on Monday.

Mossin' Around finished second to the handy sprinter It Is Written in a performance that pleased Begg.

"It was a nice comfortable trial," Begg said.

"It's not always ideal trialling on the Monday before a race on Saturday but the way the weather's been over the last 10 adays nd the unavailability of grass gallops it has made it tough."

Begg expects Mossin' Around to make further improvement following Saturday's race saying the mare's coat is still not right.

He said dropping Mossin' Around back in grade was designed to spark her back into winning form.

She has one win to her credit with four second placings from eight career starts.

"In the How Now last week (at Caulfield) there was about six rated 90 and above, so hopefully back a little bit to this grade might help her get some confidence back," Begg said.