The Showdown is restricted to two-year-olds by Victorian-based VOBIS nominated sires and Dee had the choice of two highly fancied runners in Saturday's 1200m-dash which carries a first prize of $500,000.
He partnered current $3 favourite Prince Of Sussex to victory in the VOBIS Gold Rush at Bendigo on March 30 and rode the $3.80 second pick, the John Sadler-trained Sartorial Splendor, to his debut win at Terang on April 14.
Dee admitted it was a tough choice before race experience won out with him electing to ride Prince Of Sussex for trainer Matt Laurie.
Prince Of Sussex has two starts under his belt with Sartorial Splendour starting just once.
“It was a hard decision because they're both very good horses and they're both going to improve again next preparation,” Dee said.
“As much as you'd like to ride both of them, I had to choose one of them and the one that won out was Matt Laurie's.
“It was a matter of greenness that won out.
“Probably John Sadler's horse was a bit greener when he won at Terang than Matt Laurie's, although they're both still pretty green.
“Matt Laurie's horse has probably just got the edge at this stage because he's had that extra start under his belt.”
Dee galloped Prince Of Sussex on the course proper at Caulfield on Tuesday but has not been back aboard Sartorial Splendor since his Terang victory.
He did get a look at Sartorial Splendor in a gallop at Caulfield last Saturday.
Jordan Childs, who takes over on Saturday, rode Sartorial Splendor with Dee aboard another member of Sadler's team.
While impressed with Sartorial Splendor's work, Dee was happy with his decision to stick with Prince Of Sussex.
“By then the decision had been made and I'm pleased with my horse,” Dee said.
“He's probably not as good a track worker as the other horse but he certainly turns up on race day.
“Off his Bendigo win he's a pretty smart horse.”