Australian coach Andrew McDonald has defended embattled all-rounder Mitchell Marsh’s role in the team but hasn’t declared him a certain starter for the fifth match in Sydney.

Many pundits are calling for Marsh to be dropped following a measly return during the four Border-Gavaskar matches this summer to date.

The 33-year-old is a dressing room favourite but on the field he’s produced a paltry average of 10.42 and only one score in double digits.

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It is the second lowest average by an Aussie batter in a home Test series ever (with a minimum of seven innings) – only Kim Hughes (10.12 in 1984-85) has worse.

Marsh has also contributed next to nothing with the ball since snaring a couple of wickets in Perth.

It’s led to speculation he is carrying an injury or is unfit, but McDonald batted those suggestions away when speaking to media on Monday.

“We haven’t required him with the ball as often as what we would have thought,” McDonald said.

“He bowled again today. His speeds are up in the high 120s. There are no injury concerns there.

“I think to sort of head that down that angle is a little bit unfair. We just haven’t required him at certain times for whatever reason, so that’s more a tactical implementation, as opposed to a body.

“I think the amount of overs that we’ve been bowling across the series is probably going to be a benefit to us.”

Marsh almost certainly would not have been in the Test team this summer if not for Cameron Green’s back issues, which ruled the young gun out of the entire campaign.

And there is a strong case for him to be dropped ahead of the SCG match which begins on Friday.

Complicating that, though, is the fact Australia won in Melbourne and hold a 2-1 lead in the series, and also a potential new injury to fast bowler Mitchell Starc.

Selectors may be hesitant to make multiple changes to a winning team, although Marsh’s form warrants his axing.

“Would he like better performances? There’s no doubt about that,” McDonald said.

“Over four Test matches, he hasn’t been able to deliver at the level that he would like and we would like, but yeah he’s up and about.

“We just won a Test match. He’s in a pretty good headspace.”

If Marsh is axed, all-rounder Beau Webster is in the squad and ready to make his debut.

Aussie captain Pat Cummins will confirm the line-up either at his Thursday press conference, or at the toss on Friday morning.