"It shouldn't be that big a deal and Greg [Hope, trainer] wasn't that worried about it when I spoke to him yesterday," said regular driver May.
"He was about 70 per cent on starting him this week so it wasn't that bad but he has obviously decided against it.
"It is a real shame because he trialled so well and Greg thought he was ready to go after giving him a proper workout the other day.
"But obviously it is still annoying him so it looks like he will miss this Friday."
Hope could not be contacted last night.
Friday's 2600m mobile was to be the first clash of trotting's big three in Monbet, Speeding Spur and Marcoola.
The latter two are in the nominations for Friday's Group 1 and Monbet could theoretically join them still, as nominations have been extended until this morning.
But if he doesn't then May hopes Monbet can be back on track for the Anzac Cup (April 26) and Rowe Cup (May 3), both at Alexandra Park.
The Trotting Champs won't be without real depth though as rising stars Winterfell, King's Landing and Sundees Son step up to the open class Group 1 level for the first time.
Friday night's meeting is one of the strongest of the year with the $200,000 New Zealand Derby for the pacer and the $100,000 equivalent for the trotters as well as the Easter Cup.
Ultimate Sniper retains favouritism for the pacing Derby even after an expensive last-start gallop, rated a $1.70 favourite by the TAB, ahead of stablemate Jesse Duke at $4.
Letterkenny Boy, who is third favourite in the futures market for the Derby, has not been nominated and is instead entered for a lower grade race on Friday night, so is very much a case of punters beware.
Enhance Your Calm will be unbackable in the Trotting Derby while the Easter Cup is likely to bring together New Zealand Cup winner Thefixer, Auckland Cup winner Turn It Up and Miracle Mile hero Spankem.
But the shock of that race is the entry of superstar three-year-old filly Princess Tiffany, because her high rating means there are no other races on Friday, outside the Derby, she is eligible for.
She won't be starting though, with trainers Mark Purdon and Natalie Rasmussen making a point about how poorly off the best three-year-olds, especially fillies, can be treated by the rating and programming systems when the country's best filly can't find a suitable race.