The Rock trainer was thrilled with the performance of the lightly-raced greyhound as he upstaged some of the best dogs in the country to progress through to the next stage of the lucrative series.

After coming up with the number one box, Ultimate Speed took advantage of some of his rivals misfortune to take the lead coming around the first turn after from there was never headed.

"It is a big thrill," Smith said.

"Especially for the dog and the bloke who owns.

"I'm rapt that he sent him to me."

Ultimate Speed was unplaced in his first two starts, and had been barred for failing to chase, before heading to The Rock trainer.

However Smith has been able to turn it all around and win both a heat and the regional final of the series.

He's been impressed with the transformation with Ultimate Speed's record now at five wins and four placings from 14 starts.

"He settled in and he never takes a backward step," he said.

"He just gets better and better and is a very underrated dog."

Ultimate Speed ($9) was beaten from early speed from the one box but when track record holder Deliver ($2.20) went amiss approaching the first turn and checked kennelmate Black Opium ($2 favourite) in the process, he was able to rail through to lead on the first turn.

Going on to clock 29.93 seconds with a 1.25 length win over Black Opium, Ultimate Speed is now the second fastest greyhound over the 525 metres at Wagga.

Smith won a Wagga Gold Cup with Wenzke in 2012, but rated Ultimate Speed's success better.

"This is the best one so far," he said.

"I won a Wagga Cup a lot of years ago now but we've been in the wilderness and just winning around the bush.

"He's pretty close to the best dog I've ever had, there is no doubt."

Ultimate Speed, along with the next three finishers Black Opium, There's A Catch and Perfect Marshall now all progress through to the semi-finals at Wentworth Park next month.

Smith is looking for another good draw on October 11.

"We're over another hurdle and have one to go before we make the final," Smith said.

"I just hope we can draw a box at Wenty now."