Brisbane captain Adam Reynolds suffered a suspected ruptured biceps as the Sydney Roosters powered their way to a 40-18 win at Suncorp Stadium.
Reynolds left the field clutching his left arm in the 46th minute after tackling winger Fetalaiga Pauga.
If confirmed, the Broncos skipper is facing at least three months on the sidelines in a huge blow to the club's premiership chances.
Earlier, Broncos winger Jesse Arthars was taken to hospital with a broken jaw after a head clash with opposite number Dominic Young in the 19th minute.
The Roosters led 18-6 at half-time on the back of rampant second-rower Angus Crichton's two tries.
Brisbane hit back to level at 18-all with five-eighth Ezra Mam setting up a try and scoring one of his own.
Roosters skipper James Tedesco was superb throughout and orchestrated a try for prop Terrell May to regain the lead, with Brisbane winger Deine Mariner in the sin bin for a shoulder charge on Tedesco.
Lock Connor Watson crashed over, May notched his second and Tedesco sent Young over as the Broncos ran out of fuel and the Roosters roared home.
Brisbane scored first through forward Jordan Riki after a sublime short ball from five-eighth Ezra Mam.
The Roosters hit back with a cracking try of their own, with the athletic Young throwing a superb inside pass to centre Joey Manu.
Crichton, in a purple patch of form, was on fire for the visitors on the left edge.
He made a clean break early in the match and stormed over from close range to give the Roosters a 12-6 lead.
The 28-year-old, displaying the form that has led to 11 appearances for NSW, scored his second when he supported centre Joseph Sua'alii, who threw a superb around-the-corner pass to his powerhouse back-rower.
Crichton, off-contract and mulling a code switch to rugby union, reinforced why he is one of the most damaging ball running forwards in the game.
The Roosters had lost premiership-winning stars Jared Waerea-Hargreaves (calf), Victor Radley (hamstring) and Daniel Tupou (knee) during the week but their depth came to the fore.
The Broncos were off their game in attack with fullback Reece Walsh making errors in the first half before showcasing his dazzling skills in the second.