The incumbent Test opener played a lone-hand with 141 as Victoria reached 6-266 at stumps at Junction Oval on Thursday, where a no-ball howler sparked controversy.

Harris now has three Shield centuries in finals, one for Western Australia four years ago and the other for Victoria in 2016-17.

"You always get yourself up for a final. And knowing I've done well in previous finals gives me a bit more confidence," the 26-year-old said.

The Shield's leading run-scorer brought up his third century of the season early in the final session with a single off his pads.

He was given two lives, dropped on 71 and again in the slips on 121, during a day where NSW shelled four catches.

Harris, who appears locked in a three-way battle to open for Australia in England with Joe Burns and David Warner, succumbed late to the second new ball when was nabbed in the cordon off Sean Abbott.

He said the ton was crucial, given Victoria picked four quicks and a spinner.

"Knowing that we'd come in with an extra bowler I was pretty aware someone is going to have to make a decent score," Harris said.

Seamer Trent Copeland (2-61) was the pick of the NSW attack, though one of his scalps came via a massive no-ball.

Copeland trapped youngster Will Pucovski (17) lbw before Seb Gotch (2) edged to third slip, leaving Victoria 3-113 midway through the second session.

Television footage revealed Copeland overstepped the crease by a fair margin when delivering the ball that removed Gotch.

"That's certainly not out," former Australia coach Darren Lehmann said in commentary on Fox Sports.

After winning the toss, Victoria only lost skipper Travis Dean (23) in the morning session but lost traction when Pucovski, veteran Cameron White and the luckless Gotch all fell cheaply.

James Pattinson grafted to an unbeaten 11 from 66 balls and will resume on day two alongside Chris Tremain on 13.

Abbott said NSW would move on from a poor day in the field.

"As long as the effort is there we don't really dwell on those chances that have gone down," he said.

Unlike previous seasons, a draw won't necessarily be enough for ladder-topping Victoria to lift the trophy, with Cricket Australia for the first time adopting for the final the first-innings bonus-point system used during the regular season.

Victoria finished the day on 0.66 points, while NSW has 0.6.

Australian Associated Press