Returning from a shoulder injury during Saturday evening's Battle of Brisbane against the Broncos, which the Red Hill-based outfit took out in a narrow victory, Marshall-King managed to play the entire 80 minutes.
It was a strong effort from Marshall-King, who scored a try and made 34 tackles playing at dummy half. It was his first game since a loss to the Manly Sea Eagles in Round 15.
But Bennett, speaking at the post-game press conference, revealed it could be the final game of the season for Marshall-King, with the shoulder injury believed to be an "ongoing one."
“He did (make a difference) but he's still got a bit of a shoulder problem there so I don't know how long we'll have him back for," Bennett told the media.
“Looks like it might be a bit ongoing that one. He's a wonderful player and we probably got him at about 75 per cent tonight.
“We'll probably have to go the rest of the season without him.”
The AC joint injury was originally sustained against the St George Illawarra Dragons in Round 13. His effort against Manly in Round 15 saw just half a game played.
Bennett confirmed it was the same shoulder, even though Marshall-King had managed to play out the 80 minutes.
The dummy half has had 8 try assists in 12 games this year and has been one of the best for the expansion club in what has been a surprising season.
Half Sean O'Sullivan, who started at hooker last week against the Parramatta Eels, could now spend more time at dummy half during the second half of the season, while youngster Harrison Graham may play a more consistent role off the bench.
The news gets worse for the Dolphins too, with Felise Kaufusi likely to be sidelined for the next 11 days after he suffered a concussion. The Dolphins do not have a bye next weekend in the lead-up to Origin 3, so the former Queensland representative will likely miss next Sunday's game against the Gold Coast Titans, before being a chance to return against the Penrith Panthers in Round 20.