Sri Lanka opener Dimuth Karunaratne has been cleared to play on in the second Domain Test in Canberra in a timely boost for the under-siege tourists after their opener was stretchered off the field on Saturday afternoon.

Karunaratne was expected to resume his innings on 46, and did so when Dhananjaya de Silva retired hurt after his own blow to the helmet, after Sri Lanka Cricket reported that he was not suffering any concussion issues.

The Test is being played under the ICC's playing conditions, and Sri Lanka Cricket's approach is in line with the current ICC medical policy.

Karunaratne was said to be in "good spirits" last night after he was struck by a Pat Cummins bouncer and sent to hospital.

The left-hander had been cruising along and reached 46 when he was hit in the back of the neck by a 142kph delivery from Cummins.

Karunaratne was immediately attended to by both teams' medical staff, stretchered off in a medi-cab and sent to a hospital via ambulance to be assessed.

Karunaratne said he felt pain in his neck and tingling to his fingers. His coach, Chandika Hathurusingha, provided an update on Saturday evening about the veteran opener.

"He's in the hospital at the moment and in good spirits. No danger at the moment. He was talking to us before he was leaving as well," Hathurusingha said after play.

"It was a bit scary at the start the way he fall back initially but he was OK.

"Throughout he was talking to the umpires and the physio. Hit on the back of the neck so he's being assessed at the moment."

Karunaratne received the all clear and was discharged from hospital late on Saturday night, but a decision on whether he bats during Sri Lanka's first innings will not be made until Sunday.

Cummins said the incident was "just one of those things that happens in cricket."

"Obviously it's never a nice feeling seeing someone go down like that," Cummins told Fox Cricket.

"The good thing was it looked like he was moving his hands and the physio said he seemed alright when he left.

"I wish him all the best and hopefully he's doing alright."

Australia No.6 Kurtis Patterson was close by when Karunaratne was felled and hopes his adversary will be fit to resume his innings on Sunday.

"You never like seeing that," Patterson said.

"You want your fast bowlers to obviously be aggressive and try and set them up to get the nick.

"But you never like it when players go down like that.

"I'm hoping he's OK. Hoping he can come out and bat again tomorrow.

"All of us were in a bit of shock but I think everyone is OK, which is good."