Kaiser Sun has had soundness issues and is not the easiest horse to ride or train.

But he can run fast.

That speed was on show at Flemington on Saturday as the lightly raced sprinter resumed with an all-the-way win in the Lanec Services Handicap (1000m).

Co-trainer Mathew Ellerton described Kaiser Sun as "a mad bolter" and said the four-year-old son of Danerich had had his share of problems including having had a chip taken out of a knee.

Ellerton said the horse was also "very difficult" to ride in trackwork.

"He obviously only knows one way at the moment but hopefully if we can get a bit of racing under his belt that can change," Ellerton said.

The gelding raced for the first time since May and firmed from $14 to $9 before going on to score by 1-1/2 lengths in his city debut over Nicholls Court with a long head to Eight Bills third.

"He has had his problems," Ellerton said.

"He's very quick and if he can work through his problems he could possibily win a handy race."

Kaiser Sun was balloted out of a restricted race at Moonee Valley last Friday week, forcing Ellerton to run him in Saturday company.

Ellerton was unsure where the horse would run next.

"Touch wood he pulls up alright," he said.