Dunk, Bailey help reduce Tigers' deficit

Ben Dunk has made three centuries in as many Sheffield Shield matches and is the series' top run scorer but even his best ever effort with the bat might not be enough to rescue Tasmania from their latest bind.

The left hander scored 115 at Bellerive Oval on Saturday only to be dismissed on the final ball before stumps, leaving the hosts at 4-240 and still well behind South Australia's 600-run first-innings total.

"It's a real personal achievement to get three in a row but it's bittersweet to get out on that last ball," a disappointed Dunk told reporters.

Also known for his wicketkeeping skills, Dunk focused on his batting during the off season and is proving a reliable opener in the Tigers' order.

When SA went to lunch on day two 7(dec)-600 it was Dunk who came back firing, while others failed.

Fellow opener Dominic Michael (10), Alex Doolan (six) and Jake Doran (five) were each dismissed cheaply and it wasn't until skipper George Bailey (93 not out) emerged, that Tassie looked firm.

They joined for a 167-run partnership during which Dunk made his 50 and then his ton.

"I really felt that George and I were getting us back into the game and I thought that if we could come back tomorrow and have another session we would be right back in it," Dunk said.

"Unfortunately losing that wicket at the end put us behind again."

The Tigers will now turn to a lower order that is inexperienced, knowing they need to reach 450 to avoid the follow on.

"I don't think it's just about surviving," Dunk said of Tasmania's outlook in the match.

"With 800 runs scored in two days it's clear there's runs to be had out there."

The opener commended SA's bowling attack, which was spearheaded by Nick Benton (2-45).

"I don't think I've ever probably batted as well as I have there: they made me work extremely hard."

Saturday's first session brought double centuries for SA's Callum Ferguson (213) and Jake Lehmann (205).

WATCH: Lehmann smashed maiden Shield double-ton

"It's nice to get some runs and have us in such a good position," Ferguson said of his highest first-class score.

Middle-order batsman Alex Ross (66 not out) topped up SA's total nicely, with a quick-fire knock that included two sixes and added to Tasmania's bowling humiliation.