Hooker Tani Fuga faces a race against time to be fit for Saturday's trip to Leicester Tigers after being stretchered off in the 23-16 defeat to Sale Sharks last weekend.
Fuga, 34, has been named in the squad to travel to Welford Road, but revealed to the Times on Wednesday that his chances of starting remained at 50 per cent.
He was replaced by 21-year-old Chris Brooker on Sunday after suffering a pinched nerve and a stiff neck when he got on the wrong side of a tackle mid-way through the first half.
And, with South African hooker Gary Botha already ruled out, it means Quins could go into Saturday's Guinness Premiership play-off decider in the Midlands with just Brooker and Aston Croall available.
But Fuga, who signed a one-year extension to his contract last month, has backed the pair - with just eight appearances between them this season - to take the challenge to the Tigers.
"At the moment, there is a 50-50 chance I will make it but, hopefully, the chiropractors can patch me up to get me out there. Fingers crossed," he said.
"Aston has stepped into the job before and, although Chris may not have a lot of experience, he is very quick and skilful around the park, so we should be okay.
"It is a massive game that we have to win.
"It was very disappointing to lose on Sunday, but we have an opportunity to put that right."
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