Queensland's stirring State of Origin triumph has come at a cost with prop Tom Gilbert dislocating a shoulder and double try-scorer Selwyn Cobbo troubled by a hip complaint.
The Maroons duo were hurt during their 26-18 victory over NSW at Adelaide Oval in the series opener.
Both face scans to determine the severity of their injuries, coach Billy Slater says.
Cobbo hobbled off with about 10 minutes remaining while Gilbert's right shoulder popped attempting a tackle in the 19th minute.
His injury was followed by the Maroons being penalised for having 14 players on the field - his replacement Lindsay Collins entered before Gilbert departed.
Collins and Gilbert were both in play for about 15 seconds before the error was called to referee Ashley Klein's attention.
"There was a couple of seconds that we had 14 players," Slater said.
"I thought Tom Gilbert got taken off on the other side (of the field), his shoulder popped out so he was in a pretty bad way.
So we made that call to get Lindsay on thinking that Tom Gilbert was off the field on the other side."
The Maroons could face a financial sanction for the mistake, with the NRL setting a precedent earlier this month when fining South Sydney $15,000 for playing with an extra man.
But that mistake was compounded by running out with a different starting side to their official team sheet for their round-nine win over Brisbane.
The Rabbitohs played with 14 men for roughly 20 seconds.
NSW emerged relatively unscathed from the Origin opener, though centre Tom Trbojevic was concussed and faces a mandatory 11-day stint on the sidelines.