WA trio Showmanship, Graceful Girl and Red Can Man struggled on a heavy Caulfield track as jockey Jamie Mott celebrated his first Group 1 win on Callsign Mav in the Sir Rupert Clarke Stakes (1400m).

Showmanship, who started the $5.50 second favourite, ran second last while fellow Bob Peters-owned star Graceful Girl ($26) finished a distant last.

“Graceful Girl just didn’t handle it (heavy track) at all, she just dropped out from the furlong and didn’t know what was happening there in those conditions,” trainer Danny O’Brien said.

“Showmanship was just in the wrong spot. He was back on the fence and that was not the ideal spot.”

Jockey Luke Nolen also said Red Can Man didn’t handle the heavy surface, but the Steve Wolfe-trained gelding was brave in defeat when 2 lengths eighth.

A massive downpour of rain during the Caulfield Guineas Prelude wreaked havoc at Caulfield, forcing a delay to the meeting as officials waited for surface water to clear from the track.

Mott, a hard-working and understated Victorian rider, celebrated his biggest victory when he lifted Callsign Mav ($16) to a narrow win over I Am Superman ($15).

Tuvalu, the $4 favourite for WA and Victorian trainer Lindsey Smith, was close behind in third.

Mott, 34, has ridden more than 1300 winners but only had one Group 1 placing before the Rupert Clarke.

“I always knew it was coming,” Mott said.

“I’m one for working hard and always believing in what you are doing.

“Give up is not an option.” I put myself in a good spot weight wise and mind wise this campaign and I’m thankful to Danny (O’Brien) and the wonderful connections for keeping me on Callsign Mav.

“He got conditions to suit today and he was really tough when I needed him.”

Perth Cup winner Midnight Blue also battled on the heavy track when eighth in the MRC Foundation Cup (2000m).