Waller's Queensland stable manager Paul Shailer tipped big things for McNab after the jockey won on Irish Optomism at Doomben on Saturday.
It was McNab's first metropolitan winner in Brisbane after he was lured from New Zealand to be Waller's Queensland stable jockey.
Shailer said racegoers could expect big things from McNab now he had his weight under control.
“He had a bit of trouble coming out of the New Zealand winter to here, but he's got his weight down,” Shailer said.
“If he can ride 54 or 54-1/2kg consistently, he is going to be a force to be reckoned with in the premiership here.”
McNab won a Group One race on smart filly Melody Belle in New Zealand last year.
“It is good to get going for Chris and Paul. “I'm starting to settle in now and the weight is coming off steadily. I'm loving the lifestyle here,” McNab said.
Sydney's premier trainer, Waller operates stables at Rosehill and Flemington and since opening his Gold Coast base this season, he has 40 metropolitan winners in Queensland.
That places him sixth on the Brisbane premiership for 2017/18 and he is fifth on the Melbourne table.