The six-year-old, whose annual appearances at Kranji Racetrack leave the packed stands crackling with excitement, was pulled out of the 1,200 metre sprint as a precaution.
Rocket Man was suffering a mild strain when he was denied back-to-back Group 1 Dubai Golden Shaheen wins, running second in March, but trainer Pat Shaw had been able to get him to the post to win a fourth consecutive Group 1 Lion City Cup last month.
Shaw and owner Fred Crabbia made the decision to err on the side of caution after Rocket Man failed to shake a ligament strain to his near foreleg.
Shaw described it as a "porting injury", likening it to an athlete who runs so fast that they over-reach.
"It's like twisting an ankle," said Shaw. "All it needs is rest and he will get over it.
"If we were to press on, it could cause long-term damage or even worse, irreparable damage, and that was not a risk I could take. And remember he has a screw in the other leg as well.
"He can have a good rest now and we will get him back up for his next campaign."
Rocket Man had been looking for a repeat victory in the KrisFlyer after scoring a breakthrough win last year at his third attempt.
Rocket Man's absence would appear to leave the way clear for Ireland's six-times British champion jockey Kieren Fallon on board Krypton Factor. Fallon rode his Bahrain mount to victory in the Golden Shaheen.
Other international entries for the sprint include British horse Secret Asset and Irish mount Invincible Ash.