The Tigers' third season under Benji Marshall appeared to have been dealt a serious blow when both starting halves went down in Saturday's 20-16 loss to South Sydney.
Luai hurt his left knee falling awkwardly on a kick chase in the second half, before Doueihi slipped over making a tackle in the final minutes and clutched at his right hamstring.
On Monday night, the club confirmed co-captain Luai would miss four weeks with a medial ligament injury, meaning he is likely to sit out of clashes with the Warriors, Parramatta, Newcastle and Brisbane.
But Doueihi is expected to be available for Friday's clash against the Warriors in Auckland after being cleared of serious injury by club staff.
It's welcome news for starting halfback Doueihi, whose extensive injury history includes three anterior cruciate ligament ruptures.
Jock Madden looms as a starting halves option to partner Doueihi this week, or highly rated Latu Fainu may be available as he nears recovery from off-season shoulder surgery.
The 20-year-old has resumed contact training and coach Marshall had previously estimated he would be fit by round four.
"(Fainu) has been doing his training and his return-to-play training. He's looking good, he's looking quick. I'm excited to see him go," said Tigers second-rower Kai Pearce-Paul.
Luai joins outside backs Taylan May (shoulder) and Starford To'a (foot) in the injury ward at the Tigers.
But veteran Alex Twal said injury setbacks could definitely give the club a chance to test its mettle.
"It takes a squad of 30 over the course of a season. At different stages throughout the year, you're going to have injuries and setbacks and whatnot," he said.
"It's just the way that the squad copes with that. We've built over the pre-season to make sure that whoever steps in, whatever position, they're going to do the job."
