Brunt, who took 5-60 earlier in the day, described the innings as one of the best she has seen in her career.

"All-round, the rate she scores if she wants to, even in situations like that, is next level," said Brunt.

"In Test cricket you talk a lot about [Australia all-rounder] Ellyse Perry, but batting-wise she [Knight] is the best in the world.

"Some of the mental work she does and the fight she shows is next level too."

Knight, 31, was already the only woman to score centuries in all three formats for England.

Her hundred in Canberra, her second in Tests following 157 against Australia in 2013, came as wickets tumbled around her with England 120-6 at one stage and in danger of being forced to follow on.

She batted calmly for 249 balls, did not offer a real chance and capitalised late in the day in a crucial unbroken partnership of 66 with Sophie Ecclestone, who was the next highest scorer with 27 not out.

"I have seen some brilliant hundreds in World Cup cricket and a hundred here by [England batter] Danni Wyatt in a T20 [against Australia in the 2017-18 Ashes]," said 36-year-old Brunt, who has played 239 times for England across all formats.

"I have been around a long time and seen many great hundreds but that [was in the] top three.

"Not one person has scored a significant score so she has taken the whole world on her shoulders and dug extremely deep to put a score on the board."

Perry, one of the superstars of women's cricket for more than a decade, took 2-35 for Australia on day two.

Asked about Knight's knock, she said: "It was certainly an exceptional one.

"Essentially she didn't give us a chance. It was super gritty but very classy as well.

"She is a wonderful player and has excelled in this format before. It was right up there in terms of performances."

'Probably my last Test' - Brunt

The day began with Brunt taking two wickets to earn a deserved five-wicket haul.

It came 6,001 days after her first as a 20-year-old, at Worcester in 2005 and also against Australia.

The fiery seam bowler has overcome two back operations to become England's all-time leading wicket-taker across all formats but admitted afterwards this will likely be her last Ashes Test.

"It is a question that goes around in my head most weeks - "what are you doing?"," Brunt said.

"I always say never say never but I do believe this will be my last Ashes Test."

Defeat for England in Canberra would see Australia retain the Ashes while even a draw would mean England would likely have to win the three one-day internationals that follow to take the series.

Despite Knight's century, England are well behind in the game but Brunt insisted her side can still win.

"If I didn't think that I would go home and stay in hotel room and not bother bowling 40 overs," she said.

"Sophie Ecclestone is probably not going to sleep and be in the nets about four hours in the morning to work on that maiden fifty.

"We have come in desperate for a win. The aim is 100% to win and we all believe we still can. We have seen it turn around in a way you wouldn't have thought it would a couple of hours ago. It is cricket and anything can happen."