By Mark Ryan

MELBOURNE, Aug 28 AAP - Steven Arnold was blown away by the ability of reigning Cox Plate winner So You Think after he rode him in a race for the first time to take out the Group Two Memsie Stakes at Caulfield.

The Bart Cummings trained four-year-old hadn't raced for 10 months after missing the autumn following surgery to correct a throat problem.

He showed no signs of any problems with an outstanding first-up performance.

"The sky's the limit, he really impressed me today," Arnold said.

Backed from $7 to $6.50, So You Think tracked race leader Typhoon Tracy from the outset and forged to the front in the straight.

Whobegotyou ($11) emerged as the danger in the straight but So You Think kicked strongly to hold him by a half-length with Shoot Out ($3 fav) a length away third.

"He's travelled near the lead in the run and when Whobegotyou came off his back coming around the corner he just gave me a great feel," Arnold said.

"I don't think he's 100 per cent comfortable in the ground either but his other attribute is he's a fighter as well. At the furlong (200m) he was in for the fight and held them on the line."

Arnold has ridden some top-class gallopers including Horse of the Year-winning sprinter Scenic Blast and outstanding stayer Efficient but for him So You Think is something else.

Cummings was at the Golden Rose meeting at Rosehill on Saturday and he too was super impressed with So You Think.

"You can't keep a good horse down," Cummings said.

"I've had a few good horses and he's up there with the best of them.

"It was a big effort. He had to be further forward than anticipated because of the heavy track and the backmarkers had no hope.

"He won the Cox Plate the way he was, so he can only get better and better," Cummings said of So You Think's throat problem.

"He'll probably go to the Dato Tan Chin Nam and the Yalumba and then the Cox Plate."

Typhoon Tracy ($3.10) finished a solid fourth, 3-1/2 lengths in front of fifth-placed Zabrasive.

But jockey Luke Nolen said the mare wasn't as effective in the slow (7) ground as she is on top it.

"It's a hard job to cart them to the middle of the track and do all the donkey work so I don't think she lost any fans today," Nolen said.

"She's open to improvement and we're on target for the Cox Plate.

So You Think has taken over as Cox Plate favourite at $4.40, replacing Shoot Out who is at $7.50 with Whobegotyou and Predatory Pricer at $11 and Metal Bender at $12.

Typhoon Tracy is at $21.