Mark Jackson knew he had a good horse on his hands when Craig Williams' manager called asking for the ride on maiden Niminypiminy in the Listed City of Greater Dandenong Stakes at Caulfield on Saturday.

The three-year-old made her debut at Seymour on October 31 and was beaten by the highly-fancied Danny O'Brien-trained filly Mokoro.

Jackson said he had heard about the big wraps on Mokoro at the course and to run second to her in fast time was no mean feat.

"She lived up to our expectations despite the fact that she was beaten," Jackson said.

Jackson's respect for the horse, which he bred himself, has since grown.

He says she is running times in trackwork that he hasn't seen from any of his previous horses except Apennine, which ran in the Group One Thousand Guineas in 2008.

"She has shown me more ability than just about any horse I've trained, apart from Apennine," he said.

"She runs these times with consummate ease and doesn't even look like she's going hard."

The Bendigo trainer admits to being surprised when he got the call from Craig Williams' manager, which got him out of a jam because he didn't know who was going to ride Niminypiminy.

"I know they are pretty good with their form - that's only the second or third time they have phoned me for a ride," he said.

"You generally don't have people like that on board, particularly for a maiden."

Jackson said he would learn more about Niminypiminy on Saturday than he would have had he gone to another provincial track looking for an easier maiden victory.

"I'm presuming the 1400 metres is right up her alley and, against horses of this calibre, we'll know more about her after Saturday," he said.

As for the unusual name, Jackson said it was his wife Megan who chose it because the filly looked so feminine.

"I had nothing to do with it whatsoever - but I'm taking back the reins over naming the horses," he said.