NSW Origin forward Steve Simpson will have precautionary X-rays today amid concerns he may have suffered a fractured jaw in yesterday's loss to the Roosters.

The Newcastle back-rower sustained two heavy knocks to the head yesterday but courageously played on.

Newcastle's medical staff were confident Simpson had not suffered any significant injury, but he will have scans this morning to check a painful area high on the left-hand side of his jaw.

"I think I should be all right," Simpson said.

"Hopefully there's not too much wrong.

"There might be a tiny little fracture in there . . . my bite was out a little bit. I was struggling to bite down. It was sore at the time, but even now, after half an hour, it feels a bit better, so I think I should be right."

Blues selectors, who name their line-up for the interstate-series decider tomorrow, will by sweating on the results of Simpson's X-rays.

The 28-year-old made his 13th appearance for NSW in Origin II when he was recalled after Knights teammate Ben Cross broke his thumb in the series opener.

Wearing a custom-made rubber thumb guard, Cross returned to action yesterday and, after a couple of handling errors and conceding two penalties, described his performance as "not too bad, a little bit scratchy perhaps".

"Nate Myles got a good shot on me and I dropped one ball, and then I had a play with Bedsy when I was going out and he was going unders, so we were going opposite directions and I dropped the ball there," Cross said.

"Other than that, pretty strong, I thought. It was one of those games with a few dropped balls and mistakes from both teams. A lot of people were dropping the ball, so I don't feel too bad."

NSW's disappointing performance in Origin II, when Queensland scored a crushing 30-0 win at Suncorp Stadium, did no harm to Cross's chances of regaining a position in the Blues squad.

"I've done all I can do now, and it's just up to the selectors, what they think they're looking for," Cross said.