Nic Maddinson has suffered a broken arm after copping a nasty blow in his debut JLT Sheffield Shield match for Victoria on Sunday.

The day after posting a brilliant 162 in his first innings with his new state, Maddinson was forced from the field and retired hurt after being struck by Western Australia speedster Jhye Richardson.

The left-hander had moved to 10 off 20 balls in the hosts' second innings at the MCG before a brute of a short ball from Richardson hit him on the right forearm.

After being taken from the ground for scans, Cricket Victoria later confirmed he'd suffered a fractured ulna.

He's set to be sidelined for four to six weeks, which will see him miss the start of the KFC Big Bash season with his new club Melbourne Stars.

Richardson had immediately gone to check on the batsman’s well-being as Maddinson received medical attention.

He recoiled in visible distress as the doctor performed a series of tests on his arm out in the middle of the ground. Maddinson had not been wearing an arm guard.

"To see him go down when he's batting so well is disappointing," Victoria spinner Jon Holland, who earlier took 5-65 to bowl WA out for 296, said of Maddinson after play.

"He's fitted in the group really well, he works hard, he's a good bloke,"

"We didn't know much until the Doc got out there and started pressing his thumb into his arm – it looked pretty painful.

"He's batting as well as we've ever seen him bat."

An early tea was called after Maddinson's injury with Victoria 0-13 with opening partner Travis Dean three not out at the other end.

The hosts finished day three in a dominant position, moving to 0-112 and leading by 240 with skipper Dean unbeaten on 50 and Will Pucovski not out on 51.

Maddinson's 293-ball first-innings knock came to an end on Saturday morning, having struck his ninth first-class century in his maiden knock for Victoria.

The former Test batsman crossed from NSW over the winter and despite playing a key role in the Vics' JLT One-Day Cup victory at the start of the season, he had to wait for his chance at first-class level.

Maddinson finally got his opportunity after Peter Handscomb, Aaron Finch and Marcus Harris were all called up to the Test side, grabbing it in emphatic fashion by batting the entirety of Friday’s first day in temperatures nearing 40 degrees.

The 26-year-old has stated his desire to return to Test level after his all-too-brief stint two summers ago and said having to win his spot in Victoria through hard work and weight of runs, rather than being daunting, has spurred him on.

"The biggest thing is I've had to come somewhere new and put runs on the board to earn selection," he told reporters on Friday.

"In a way I think I haven’t had to do that a hell of a lot.

"I started quite young in New South Wales and was always doing enough to stay in the team without having to be a match-winner or scoring a lot of hundreds.

"The thing in Australian cricket at the moment, everyone wants hundreds so that's my focus.

"There's a little more responsibility (in Victoria) put on the player and they trust that you're doing the right thing and getting the most out of yourself. It's a fairly relaxed environment."

The ton put him in the rare club of having scored centuries on first-class debut for two states, having struck 113 in his maiden outing for the Blues as a teenager more than eight years ago.