Australian lock Darcy Swain has been slammed for appearing to deliberately target the leg of Quinn Tupaea during the All Blacks' controversial 39-37 victory over the Wallabies.

In the 35th minute of the clash, Swain dived with force into Tupaea's knee as the All Blacks midfielder was engaged over the ball in a ruck.

Tupaea went down in pain and faces a risk of serious injury after his left knee buckled inwards.

He was helped off the field by medical staff and was later seen in a knee brace. There was no immediate update on Tupaea's condition, but the incident sparked fears of a potentially long-term injury.

Quinn Tupaea receives treatment from medical staff. Photo / Photosport

The television match official Ben Whitehouse reviewed the incident before referee Mathieu Raynal decided that Swain deserved a yellow card.

"That is your responsibility to not put yourself in a reckless position which can seriously injure the player," Raynal told Swain after reviewing the footage. "You cannot target the lower legs, it's dangerous so it's a yellow card."

Darcy Swain appeared to deliberately target the leg of Quinn Tupaea. Photo / Sky

The Wallabies were reduced to 13 players after Tom Wright was also sent to the bin shortly before for cynical play.

Fans and pundits took to social media to criticise Swain's act, with many saying he should've seen red.

Former All Blacks first-five Lima Sopoaga was one of many calling for a lengthy ban for Swain: "Hope there is a lengthy ban for rubbish like this."

Former England No 10 Andy Goode described the foul play as "shocking", while also adding that Swain should've been red carded.

Swain was also involved in controversy during the Wallabies' test series with England earlier this year when he was sent off for head-butting England lock Johnny Hill.

Swain later justified the head-butt by revealing that he was goaded by Hill throughout the first test in Perth: "I was angry that he was assaulting me like this, and I wanted him to get the message it wasn't okay."