Tigers top order Ben McDermott (54) and Jordan Silk (49*) have batted Tasmania back into a strong position during the second innings, after the home side's Sheffield Shield quicks routed South Australia at Blundstone Arena today.

The Tigers led by 169 runs at stumps on day two after earlier dismissing the Southern Redbacks for just 136.

South Australia lost a stunning 7-37 in Wednesday's second session, with skipper Travis Head (49) playing a lone hand.

Head would no doubt have preferred his team mates to hang around a bit longer in his final hit-out ahead of Australia's first Test against India on December 6.

Still, the 24-year-old, who made his Test debut against Pakistan in the UAE, was last week guaranteed a spot in Australia's top six by national coach Justin Langer.

He scored 86 and six in the previous Shield match against Western Australia and three single digit scores in Australia's ODI series against South Africa.

Tigers paceman Gabe Bell led the charge and finished with 4-29 from 16.1 overs, while debutant Alex Pyecroft took 3-36 from his 12 overs, including a reflex caught and bowled off his fourth delivery for the figures of 1-0 after his first over.

The Tigers finished the day at 3-120, with Jordan Silk and George Bailey - who is yet to score - at the crease, after Jake Doran was frustratingly caught behind for 10 in the final over of play.

In his return from national limited overs duty, McDermott hit his quick-fire half century on a tricky Bellerive Oval deck.

South Australia looked solid at 3-77 at lunch but it all went pear shaped after the break.

Pyecroft sparked the collapse when he had Jake Lehmann (28) edging to slip.

Tom Cooper, Alex Carey and Joe Mennie then fell in consecutive overs without scoring, to make four ducks total for the innings, with only four Redbacks reaching double figures - 13, 49, 28 and 11.

Head was given out cutting Riley Meredith (1-23) to wicketkeeper Tim Paine but was visibly disappointed with the umpire's decision.

"I didn't think I hit it. It is what it is though," he said, adding: "On a wicket that's offering something the whole time we weren't good enough."

Pyecroft had his maiden first-class wicket when he dismissed opener Conor McInerney off his fourth ball.

"There was a bit of a carry-on with the celebration, I was pretty happy," Pyecroft said after the close of play.

"I only got the call up to play at training before the first day - they told me just before I ran out to train - so it was pretty exciting and totally unexpected.

"It took me back a bit as I wasn't really expecting it at all, but I feel very honoured obviously and loving the opportunity.

"I've just tried to ply my trade and do what I normally do - had a couple of opportunities in the Futures League after plenty of grade cricket - and luckily enough it's paid off and worked for me today.

"I was feeling pretty nervous standing at the top of my mark before my first delivery, but I just sort of had to think 'it's just another game of cricket really' and just do the normal stuff.

"So I was pretty excited to get that wicket on my fourth ball - it was good to have an impact, and I think we bowled pretty well in partnerships the whole day - Jackson and Belly were excellent I thought.

"We took four wickets in four overs there at one stage so I was pretty happy to be part of it.

"It was tough going for us during that first day but our batters have really come back well today and put us in a good position."

The Tigers scrapped 185 on day one after being sent in, with new captain Matthew Wade (43) top scoring.

Redbacks' quick Daniel Worrall took 4-42 to follow a 10-wicket haul for the match against Western Australia in his return from injury.

Worrall (3-32) also has all of Tasmania's second innings wickets.