Mitchell Starc's involvement in the remainder of the second Test is under a cloud after Australia confirmed he's suffering from hamstring tightness.

Starc didn't bowl during the final session of day two after an initial four-over burst in Pakistan's second innings, while he fielded in the slips for parts of day two as Australia carefully managed their prized fast-bowling asset.

The left-armer looked in discomfort at times but while he spent some time off the ground, he has fielded for the majority of Pakistan's second dig.

While Australia are confident he'll be able to play out the remainder of the match, the left-armer looks to be in doubt for the upcoming T20 campaign against Pakistan as Australia confirmed his pace partner Peter Siddle has been added to the squad for the three-match series.

"It’s just a bit of management of Mitch," Aaron Finch said of Starc. "Obviously the conditions are pretty hot, so trying to look after the fast bowler.

"As far as I know he is (okay). He bowled with enough pace today."

Starc has taken four wickets at 42 for the series but remains Australia's key strike weapon and it would be a major setback for the tourists should he play a limited role at the bowling crease for the rest of the Test.

Paksitan were in a dominant position at stumps on Wednesday in Abu Dhabi, taking their second innings score to 2-144 and extending their lead to 281 after Australia meekly folded for 145 earlier in the day.

Australia will also be cautious not to overcook one of their most important players ahead of the home summer, with a one-day World Cup and an Ashes series - both to be held in the United Kingdom - also on the horizon.

The 28-year-old has conceded he won't be able to play every game for Austraila despite being a first-choice player in all three formats.

"You know you can't play every game over a 12-month period purely because of how much cricket we've got these days," Starc told cricket.com.au ahead of the second Test.

"You’ve got World Cups and Ashes and Indian test series, they're big series. Tests are always going to be the pinnacle for me, that's what I what want to put my hand up and play first and foremost.

"If I'm honest with the medical staff about how I'm going with my body, if I do have niggles or that sort of thing especially when you have guys coming back and we've got a good stock of bowlers.

"In the end we're trying to have the best result for Australia and if that's someone else (getting picked) who's closer to 100 per cent than I am, if that means it's going to be the difference between winning a game or not, that's the best thing for the team."

Starc had also been set to play his first T20 at any level for two years in the forthcoming series against Pakistan, which will also feature an official game against the UAE, but Australia will likely take the cautious route if his hamstring doesn't fully heal after the second Test.

Siddle hasn't played a limited-overs match for Australia in eight years but his recall to the T20 squad comes after he reinvented himself as a death-bowling option to help the Adelaide Strikers to their maiden KFC Big Bash League title.

Speaking to cricket.com.au earlier this year, Siddle admitted he held out next to no hope of a recall to the national T20 side ahead of his first ever overseas T20 stint with county side Essex.

"I'd never played a full season of the Big Bash, I'd only ever played games here and there," he said of his T20 bowling.

"I'd played a bit of it for Victoria before there was all the T20 hype and it wasn't as big as it is now. I'd done okay but there wasn't as much emphasis on the skills.

"It was nice to get through last season's Big Bash and trial a few new tricks, come up with a few and succeed in the heat of the battle."