Ruling out a concussed Steve Smith from the third Ashes Test at Headingley was a "no brainer" really, said Australia head coach Justin Langer, two days before the start of the encounter on Thursday (August 22). 

An in-form Smith, who has struck two hundreds and a 92 in three innings this series, fell down immediately after receiving a blow to his neck off a very quick bouncer from England pacer Jofra Archer on Day 4 of the last Test at Lord's. 

He was ruled out midway through that game and had to be replaced by Marnus Labuschagne, Test cricket's first-ever concussion substitute, for the second half of the drawn game. 

"When we followed the protocols he(Smith) was probably a couple of days off being fit to be selected," Langer told reporters this Tuesday. 

"It was really a no-brainer. He felt a bit better yesterday but he's not going to have enough time to tick off everything he's got to do."

Langer equated Smith's sabbatical to James Anderson's after he aggravated a calf injury at Edgbaston and couldn't be fit in time for the second Test. 

"It's not unlike England losing James Anderson. He's arguably their best bowler and we're going to lose arguably our best batsman for this Test match," he said. 

"It is always a blow. No doubt about that. When you take your best players out it always has an impact."

"We have to make sure our senior players and the younger guys step up and fill what are almost unfillable shoes because he's the best player in the world."

Smith now has two weeks to be ready for the fourth Test in Manchester, which starts on September 4, with a three-day tour match in Derby from August 29-31.

(Inputs from AFP)