Injured Australia star Nathan Lyon insisted he had no regrets about risking further damage to his torn calf during his extraordinary innings at Lord's on Saturday.

Lyon had been unable to take part in the second Test since suffering what looks certain to be a series-ending calf injury while fielding on Thursday.

But the off-spinner made a remarkable cameo appearance towards the conclusion of Australia's second innings.

With Australia desperate to set England as challenging a target as possible, Lyon agreed to effectively bat on one leg.

Unable to walk properly, Lyon hopped down the Pavilion steps before slowly limping onto the pitch.

The 35-year-old's gutsy effort could prove vital to Australia's hopes of winning the second Test.

He hit one four and stuck around for 13 balls in a last-wicket partnership of 15 with Mitchell Starc before being caught by Ben Stokes off Stuart Broad.

Lyon departed to a standing ovation and, although the veteran bowler clearly put his health on the line, he was adamant he would do the same thing again to help the reigning world Test champions.

"I will do anything for this team. I knew the risks. It was my call. I wanted to bat," Lyon said.

"You never know how big a 15-run partnership can be in an Ashes series.

"I was proud of myself but if it was tomorrow I would do it again. I love this team."

Of his unusual experience of waiting to bat surrounded by spectators in the Long Room, of the Pavilion, Lyon added: "I had to go and wait in the Long Room otherwise I would have been timed out.

"It was pretty interesting. Everyone was looking at me. It was like being in a zoo.

"(England bowler) Jimmy Anderson asked me am I stupid and I said yes!"

Lyon is set to discover on Sunday if he has any chance of playing again in the five-match series, but that possibility looks unlikely.

"I've got a decent tear in my right calf. Regarding the series, I'm seeing the medical team tomorrow and we will have a chat about that," he said.

"Right now I'm pretty gutted, it's shattering to be honest. I've been in tears, I've been upset and hurting."

- 'Emotions are high' -

England need 257 runs to win and level the series on the final day as they chase a Lord's record 371.

Lyon, who left the press conference on crutches, is confident Australia can take a 2-0 series lead on Sunday.

"Our confidence is extremely high. We have a world-class bowling attack. There's a lot of belief in that dressing room and so there should be," he said.

Australia's task would have been easier if England opener Ben Duckett had not been reprieved when Starc caught him on the boundary.

TV umpire Marais Erasmus reviewed the replays and decided Starc did not have control of his motion before sliding the ball across the ground.

"Emotions are high (among the Australia team) but obviously there is a rule in the cricket world where you have to complete the catch. I'm not going to give you my opinion!" Lyon said.

With Duckett and England captain Stokes -- no stranger to match-winning Ashes heroics -- unbeaten at the close of play, batting coach Marcus Trescothick said the hosts believe they can win.

"We are a positive team that seizes the opportunity to do things slightly differently and do special things," he said.

"We know the history. We have talked about it many times. While Ben (Stokes) is there, we are still pretty hopeful."

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