Starc surprised when asked to bat

An injured Mitchell Starc says he was surprised when skipper Steve Smith called on him to bat in the thrilling final stages of Australia's third Test win over New Zealand.

Starc had batted at No.11 in the first innings, below Josh Hazlewood and Nathan Lyon, and slammed a quickfire 24 from just 15 balls despite obviously struggling with his foot injury.

WATCH: Starc swings hard in crucial cameo on day two

But with Australia needing two runs to win and with three wickets in hand late on Sunday, Starc came out to bat at No.9 despite still not being able to run freely.

After slamming his first ball straight to the cover fielder, Starc was at the non-striker's end when Peter Siddle hit a Tim Southee delivery through point.

The duo set off for the winning runs, with Starc hobbling and hopping his way up and down the pitch as Australia celebrated the win.

Smith said after play that Starc didn't risk worsening his injury by batting, but the left-armer added he was surprised to bat at his normal No.9 position.

When asked on Monday morning why he walked out to bat, Starc laughed and responded: "I'd like to ask Steve Smith the same question".

WATCH: Starc speaks about being asked to bat

"The spinners were on, so (Smith) asked if I'd go out there and have a slog," he said.

"I thought that might change when they took the spinner off but it ended up that I went out there.

"While the Marsh’s were out there and V (Adam Voges) I was quite comfortable out on the couch in the back just watching. 

"Still nervous but watching. But things happened pretty quickly and I had to get the pads on. Was an interesting little period of play but glad we got over the line."

Starc picked up three crucial wickets on Friday before he was forced from the field and didn't bowl again in the Test.

WATCH: Starc limps off with injury on day one

Scans showed the early stage of a stress fracture, with the left-armer aiming to make a comeback for the return series against New Zealand in February.

Smith said his quick didn't risk further injury by walking out to bat.

"The damage is done," Smith said.

"He's a great team man and I was thankful for him to be able to go out there and have a crack.

"He put his hand up, which is what he always does for the team.

"Unfortunately (he) hit one to the fielder, but he hobbled through for two off Peter Siddle's bat and it was nice to get those two runs to get us over the line."