Smith battles on for brave hundred

Steve Smith has produced one of the most courageous knocks of his Test career, crafting a century in Christchurch despite being struck on the helmet by a bouncer.

Quick Single: Second Test, day two report

On day two of the second trans-Tasman Test, Australia's skipper was on 78 in the final over of the second session when he attempted to duck and weave out of the way of a bouncer from Neil Wagner, but the delivery kept low and hammered the side of his helmet.

The 26-year-old hit the deck as team doctor Peter Brukner rushed out.

Smith was back on his feet soon after, with Brukner assessing the skipper for signs of concussion.

He was quickly cleared to bat out the over.

But the disquiet at Hagley Oval was palpable as Smith's batting partner Joe Burns, girlfriend Dani Willis and everyone in the sold-out crowd looked on.

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"I ran up straight to him and he sort of flashed his eyes a little bit," NZ paceman Wagner said.

"I was a bit worried at the start.

"Then he said he's fine and he took a bit of time.

"A hell of a lot of credit to him to take a blow like that and stand up and bat the way he did.

"It shows the character of the bloke he is."

Notably, Smith wasn't wearing the helmet attachment that was released following Phillip Hughes' tragic death in 2014.

"Certainly it's always a concern when you see someone get hit in the head," Burns said. "It got him quite flush as well, which was a concerning part.

"But fortunately the medical staff were out there very quickly.

"Luckily, the tea break was just around the corner."

Wagner dug the next ball in short but Smith pulled it for a single then headed to the rooms.

"It gave him a chance to sit down for 20 minutes and I guess just let the shock settle," Burns said.

"Then, yeah, he came out after tea and was 100 per cent.

"He got a new helmet and just had 20 minutes to reset himself."

Smith walked out to bat after tea without any signs of discomfort then proceeded to see off the second new ball with minimal fuss.

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He went on to score 138 before being caught by Martin Guptill off a short ball from Wagner.

Wagner, who peppered Smith with bouncers for much of the day, felt "shaky" after striking the batsman.

"It's not nice, is it," he said. "It's never one's intention to hit someone in the head and see him go down like that."

Smith was also struck in the midriff in the penultimate over of the first session when he misread a ball from Trent Boult.