Scans will determine whether David Fifita has potentially played his last game for the Broncos after the Titans-bound second-rower injured his ankle against the Eels.
Fifita was helped off Bankwest Stadium in the 42nd minute of Friday night's 26-12 loss after landing awkwardly in a tackle that resulted in Eels prop Junior Paulo being placed on report by referee Henry Perenara for a "duty of care" violation.
Fox League reported the star forward is suspected to have a low-grade ankle sprain, providing some hope that he could make a quick recovery for next week's final-round clash against the Cowboys.
The Broncos need to win the local derby and hope the Bulldogs lose to Penrith to avoid the first wooden spoon in their proud history.
"He will go for scans [on Sunday], I spoke to him then," Gentle said of Fifita.
"He tried to come back out but I think he said they had him doing some hopping [tests] and whatever and it wasn't right."
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The Gold Coast, who Fifita will join on a rich deal next season, and the Queensland Maroons, who he is expected to represent in November, will be sweating on the severity of his injury.
Meanwhile, Gentle said the Broncos "showed a lot of effort" in the five-tries-to-two defeat and are "actually playing for each other, playing for our fans, playing for our sponsors".
"There's a lot of pride in what they're doing at the moment," he said.
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And they have much more than simply wanting to climb off the bottom of the ladder as motivation against North Queensland, with club legend Darius Boyd to play the final match of his illustrious career.
"We're expecting a chance to get the biggest crowd of the round with the Queensland derby back at Suncorp. We'd like to fill it as much as we can," Gentle said.
"We've known for quite a while now where Darius's finish line was. We'll have to send Dave [Fifita] off as well – that's in the balance. We'll be doing everything to send Darbs out a winner.
"We owe it to everyone to put in a really good performance back at home."
Gentle said playmaker Tyson Gamble is unlikely to be available after being concussed in the first minute, while five-eighth Brodie Croft was knocked out at training during the week.
But he expects star prop Payne Haas to return after a week off for family reasons.