Cameras spotted Panthers teammates congratulating Koroisau on Saturday night when he learned he would play for the Blues in game two in Perth.
The 29-year-old hooker made his Origin debut in game three last year, but it was later revealed he had broken COVID-19 protocols by sneaking a woman into camp before the game.
READ MORE: Origin star in $2.4 million Dolphins snub
He was named in Brad Fittler’s squad for game one this year, but didn’t make the final 17.
Now, though, it appears he will pull on a jersey next Sunday in a must-win game.
Fittler credited the Panthers star’s competitiveness as one of the reasons behind his inclusion for game two.
“(We want him to do) what he does for Penrith,” he told 9News Sydney.
“He tests the ruck and the other key to Api is he defends well and is a great competitor, that’s the key.”
Fittler made a total of seven changes to his NSW Blues side that lost game one 16-10 at Sydney’s Accor Stadium.