Leaving the field with around a quarter of the game to go, Smith will now need scans to confirm the extent of the damage.
Roosters' coach Trent Robinson confirmed the injury post-game, but said he was unsure of how long the hooker would be sidelined for.
"I just talked to him. It's probably a fractured thumb," Robinson said during his post-game press conference.
"I don't know what that means, what length of intervention that takes."
The NRL Physio said the typical recovery time is between four and six weeks for the injury.
Suspected broken thumb for Brandon Smith, scans to assess in coming days. If break confirmed often return to play range is 4-6 weeks (can vary with fracture type/specific location). If surgery is required doesn’t always mean maximum recovery time, can speed up early rehab
— NRL PHYSIO (@nrlphysio) May 19, 2023
It's likely Jake Turpin will start during the weeks Smith is out of action for the tri-colours, with the Roosters to face the Canterbury Bulldogs, Penrith Panthers, Newcastle Knights, Canberra Raiders and Manly Sea Eagles over the next six weeks in between a pair of byes in Round 13 and Round 19.
The return of Sam Walker from a knee injury - assuming he slots back into first-grade with Joseph Manu also working through the rehabilitation of an ankle ligament injury - will likely push Drew Hutchison back to the bench where he will spend some time on the park at hooker.
The injury is believed to be the only concern out of the game on that front for the Roosters, however, the club are also facing an extended period without Victor Radley.
The lock forward was cited for striking after a headbut during a scuffle between the two sides in the first half, and the Grade 1 charge - given it's his third offence - carries a three-match ban with an early guilty plea, or four if he fights the charge and loses at the judiciary.