Sportal.co.nz 18.Nov.2013Getty Images
Ireland coach, New Zealander Joe Schmidt said a hamstring injury suffered in Ireland's 15-32 loss to Australia would leave British and Irish Lion Sexton in doubt.
Sexton will have a scan on Monday in a effort to determine the extent of the injury.
"He has a hamstring injury, we're just not sure of the extent of the injury at the moment. To be honest it's too early to tell," Schmidt said.
"He felt it wasn't particularly bad and he pulled up quickly. But it's out of our control, we just have to wait and see what happens and wait for the results of the scans," he said.
Schmidt said he didn't think Ireland had advanced their game from their win over Samoa a week early and that had been disappointing because the plan had been to make progress week by week.
But Ireland's captain Paul O'Connell said the side had been 'far too slow' to adapt to their new coach's methods.
There was a struggle for the side in blending the supreme accuracy developed by Leinster under Schmidt's control and the passion and fire of the Munster game.
"Joe talks about the inches in rugby matches, and I think Australia won a lot of them.
"They got a few scrum turnovers, and a few at the breakdown too.
"You could see how high their emotion was in comparison to ours when we got our turnovers, and that was disappointing from our point of view.
"I suppose for a few of us we've a little bit to learn under Joe, there's a lot of technical stuff we need to get right.
"But you can't lose track of that intensity and that aggression that's required at Test rugby as well," he said.