Jim Byrne was shocked to learn Satirical Lass had shaved more than a second off the class record after he guided her to victory in the first race at Doomben on Saturday.

The mare started at $9 but won like an odds-on favourite, taking out the Country Music Raceday Plate (1200m) by five lengths over Kalandula ($10) with $2.40 favourite Lesley's Choice another short neck back third.

Satirical Lass clocked 1:08.66 to win class six race, smashing the previous record of 1:10.23 held by handy mare Skating On Ice.

"The time surprises me a bit," Byrne said.

"I didn't think we were going that fast. But I was able to get her into a rhythm and she is the type of mare who can roll along when she gets into stride."

The victory gave Byrne, who turns 45 on Tuesday, his 67th metropolitan win for the season and an unbeatable lead in the Brisbane jockeys' premiership, a title he has won three times.

He believes his season could have been even better with a bit of luck.

"A few things haven't gone my way this season but I had a pretty good winter and it has generally been okay," Byrne said.

Tony Gollan, trainer of Satirical Lass, needs two more city wins to equal Bruce McLachlan's record for most number of Brisbane wins in a season with 78.