Jonny Bairstow thinks it is "unquestionable" that Moeen Ali merits a place in the England side and says the final Ashes Test is not a time to experiment.
Moeen has endured a torrid tour of Australia, failing with bat and ball as Steve Smith's side regained the urn by winning the first three Test before securing a drawn on a flat MCG pitch.
Bairstow has backed Moeen to come good and said now is the time to get behind the struggling all-rounder.
"The guy is the second-fastest ever to 2000 Test runs and 100 Test wickets," the wicketkeeper-batsman said when the tourists arrived in Sydney for the fifth and final Test, which starts on Thursday.
"It's unquestionable to even think that he's not in our best XI. He wouldn't have played the first four Test matches if he wasn't.
"There's not many finger-spinners that will come to Australia and bowl teams out. It's very important that we get behind Mo. He can take a game away from you, and whether it be the next game or the first Test in New Zealand, the capabilities of Moeen Ali are unquestioned."
Leg-spinner Mason Crane has been waiting in the wings for a Test debut, but Bairstow does not want England to make changes for the sake of it when they attempt to build on a much-improved display in Melbourne.
"You've got to play your best team," he said. "We're still in it to win games of cricket. Whether that's Mason playing, the XI will be going out to win this next Test match.
"Yes, the series has gone. But you can see from the spirit that the guys showed in the last Test match that by no means is the foot off the gas. We're very proud to play cricket for England. We're indebted to the guys coming out, the best fans in the world.
"We've been pretty close in all the Test matches, a session and a half either way. It was exactly the same in Melbourne.
"To put a substantial total on the board and then to apply ourselves with the ball like we did was a great effort, and in that second innings to have them effectively 16-4 gave us a really good chance to win that Test match."