Udyta Clarke has had countless problems with sprinter Rich Charm and at times wondered whether he would return to racing.

The pair were the toast of the 2017 Melbourne Cup carnival when Rich Charm won the Linlithgow Stakes and they return to Flemington on Saturday for the Listed Straight Six (1200m).

Rich Charm has won only one race since, the VOBIS Gold Sprint at Caulfield in April 2018, but did spend 15 months away from racing.

Clarke said Rich Charm's problems stem from an unplaced run in the 2018 Newmarket Handicap at Flemington, even though the sprinter came out to win his next at Caulfield.

After five more starts, Clarke eventually bit the bullet, ordering scintigraphy for Rich Charm that revealed bone bruising to the gelding's fetlocks which was later followed by a hock infection.

A long recuperation and steady build-up saw Clarke take Rich Charm to Mornington in March where the gelding finished 11th behind Diamond Effort in the Listed Hareeba Stakes.

"He was terribly unlucky that day, climbing all over them, but it showed me he was back," Clarke said.

A return to Caulfield for a third attempt at the VOBIS Gold Sprint, having also won the race in 2017, was planned for April 18, but a jump-out at Cranbourne two weeks earlier had Clarke concerned.

Clarke received a favourable post-trial report from rider Daniel Stackhouse but understanding Rich Charm as she does, she knew all was not right and ordered a blood test.

"When he got that infection in his hock his immune system over a period of time has let him down," Clarke said.

"The vet said he might have been on the cusp of starting a virus when he went to Mornington and when his blood came back it showed his immune system had collapsed.

"He was locked up for three weeks and the only thing I could do with him was give him a swim.

"Three weeks later I got another blood on him and he was back to normal."

A jump-out at Cranbourne on Monday when ridden by Patrick Moloney, who takes the ride on Saturday, showed the trainer Rich Charm was ready for another start.

"Patrick said you've got to start him somewhere, so we'll go around on Saturday and see what happens," Clarke said.