The Tigers' sorry Thursday night at Cbus Super Stadium was compounded when halfback Luke Brooks sustained a hamstring injury.
Koroisau left the field in the 15th minute after attempting to tackle Gold Coast and Queensland prop Tino Fa'asuamaleaui.
Fox Sports commentator Corey Parker said he had spoken to a dejected Koroisau, who confirmed the extent of the injury.
The injury-hit Blues are likely to recall South Sydney's Damien Cook as Koroisau's replacement for game two of the Origin series in Brisbane on June 21.
Fa'asuamaleaui, who was man of the match in an inspirational display, was put on report for dangerous contact after the Bunker analysed the Koroisau incident.
The Maroons face a nervous wait before the match review committee (MRC) makes its verdict on Friday.
Fa'asuamaleaui was fined by the MRC for making forearm contact with the head of Canterbury hooker Reed Mahoney in round 12.
Fox Sports expert and former NSW hooker Michael Ennis said from the available angles he did not believe "the intent (by Fa'asuamaleaui) was what it was against the Bulldogs".
Fa'asuamaleaui was a man on a mission in defence and put huge hits on Tigers' trio Shawn Blore, Jahream Bula and John Bateman in an immense performance with and without the ball.
His second-half try sealed the deal for the Titans after they led 16-6 at the break.
If Fa'asuamaleaui is suspended and ruled out of Origin then his Titans teammate Moeaki Fotuaika could well replace him in the Queensland side after another powerhouse display.
Titans fullback AJ Brimson returned from a month's absence due to a hamstring injury and ignited his side. Brimson stepped his way over to score in the first half with electrifying speed and put No.6 Jayden Campbell in after unveiling a sublime grubber.
Campbell snaffled a vital intercept in the second stanza when the Tigers threatened and winger Phil Sami scored from it in his 100th NRL match.
The Titans had squandered five half-time leads this season but there was to be no fadeout on this occasion despite exciting fullback Bula sitting Fa'asuamaleaui on his backside with a ferocious fend and streaking away to score.
The 16th-placed Tigers were well off the mark and the Titans showcased steely resolve in defence to move to 16 competition points and stay in the finals race.
7°C