Imported galloper Instrumentalist has earned his ticket into one of the major spring staying features with a narrow victory in the Mornington Cup.

The Chris Waller-trained stayer arrived in time in the $350,000 Listed feature on Wednesday to score a grinding win over the Gai Waterhouse-trained Travolta.

The winner of the Mornington Cup (2400m) earns an automatic entry into this year's $3 million Caulfield Cup.

Instrumentalist ($16) had won three of his past five starts in lesser company and took another step up, sitting midfield under Craig Newitt before getting to the outside and finishing strongly to beat topweight Travolta ($8) by a short neck with outsider Macedonian ($101) another long head away third.

Favourite Prince Of Penzance ($3) appeared set for victory when he hit the front in the straight after settling in the box seat, but he couldn't go on with the job and was overhauled late to run fourth.

Waller's Melbourne stable representative Justine Hales praised the ride of Newitt and said earning the Caulfield Cup exemption was brilliant for the gelding's owners.

"They were so excited. I think they picked him up over the line the amount they were cheering," Hales said.

"Craig rode him brilliantly. He waited and didn't take off too early.

"He got a cart into the race and he knew the horse was honest and just tries so hard.

Hales said Instrumentalist had earned a spell after a successful preparation while Newitt praised how genuine the stayer was.

"All he wanted to do was relax and then when they bunched up from the 700 metres he picked up underneath me," Newitt said.

"He got to the outside, quickened nicely and sustained his run."

Travolta will head to the Auckland Cup next after finishing between runners closer to the inside to just miss out.

"I thought it was a terrific run, Waterhouse said.

"He's just a war horse."