North Queensland forward Josh McGuire is under an injury cloud ahead of the State of Origin series opener on June 5.

McGuire suffered a calf injury in the Cowboys' 28-14 win over the Titans on Friday night, and left the field after 28 minutes.

While the Maroons forward is set for scans to determine the severity of the injury in the coming days, Cowboys coach Paul Green could only hope the injury wasn't bad enough to keep him on the sidelines for long.

"Hopefully it's not too bad. It's probably just a low-grade calf strain so we'll assess it over the next couple of days and get a better reading on it," Green told the media post-game.

"Until we know the extent of it I can't really speculate too much."

McGuire will be hoping scans determine the injury is just a grade one tear, with a grade two tear all but ruling him out of the series opener.