JONNY Bairstow has given his unequivocal backing to under-fire England all-rounder Moeen Ali.

As England seek to break their 2017/18 Ashes duck in the final Test of five in Sydney from 3-0 down, Moeen's place in the team is being questioned after his miserable tour so far.

Moeen has mustered just three wickets, at the alarming cost of 135 runs each, and hit 136 runs at an average of under 20 an innings.

They are woeful statistics for a player who arrived in Australia as an inked-in selection but has been unable to recover his form.

A side strain ruled him out of England's first two warm-up matches and then a finger injury on his bowling hand curtailed the effectiveness of his off-breaks in the opening two Tests.

After the fourth Test was drawn in Melbourne on Saturday, captain Joe Root predicted Moeen will do more "great things for England in the future" but did not specify whether they may begin in the new-year Test at the SCG.

Yet on his arrival in Sydney, wicketkeeper Bairstow appeared confident he will be taking the field with Moeen this coming week.

Asked if the 30-year-old all-rounder is still in England's best team, Bradford-born Bairstow said: "Absolutely, yes.

"The guy is second-fastest (England player) ever to 2,000 Test runs and 100 Test wickets.

"It's unquestionable to even think he's not in that best XI. He wouldn't have played the first four Test matches if he's not in that first XI."

Moeen's paltry returns with the ball contrast with the success of his opposite number Nathan Lyon, who has taken 17 wickets.

They include dismissing Moeen six times, every time Lyon has bowled at him in this series.

Bairstow said: "There aren't many finger spinners who will come to Australia and bowl teams out.

"It's very important we get behind Moeen – he can take a game away from you.

"Whether it be this next game, whether it be the first Test match in New Zealand, the talent and capabilities of Moeen Ali are unquestionable."