Mr Marbellouz was slightly slow to go and could not lead but Nothdurft showed judgment beyond his years to work into fourth place one off the fence.
Toowoomba based Nothdurft didn't ride his first metropolitan winner until January but has since ridden 22 city winners.
“I knew he was a good horse and I didn't panic when I couldn't lead. But we had the second horse in our sights for most of the straight I was always confident we would get him,” Nothdurft said.
“There is something about him which makes me feel he will make it,” Kemp said.
Mr Marbellouz had been beaten in Listed company at his previous two starts but a return to Doomben was the key to him.
The gelding's Doomben record now stands at seven starts for five wins and two seconds.
“He does like Doomben and the wet track was no worry for him. Maybe a race like the Chief De Beers Stakes at Doomben next month could be up his alley,” Kemp said.
“I would like to win more black type with him but I don't want to rush.”
Robbie Fradd thought he had stolen the race when he kicked two lengths clear at the 300m mark.
“The winner only just got us and it was a very good run,” he said.
Sean Cormack said his mount No Annamossity, who finished third, was on the comeback trail with longer distances beckoning him.