Luai had a mixed reunion with the Panthers, playing a hand in all of the Tigers' three tries but gifting Penrith penalties ahead of two game-defining scores in Sunday's second half at CommBank Stadium.
The Tigers' co-captain almost helped his team to victory in the final 10 minutes when Jack Bird regathered his bomb close to the line and offloaded to Jahream Bula.
But a miraculous cover tackle from Scott Sorensen and Nathan Cleary stopped the fullback inches short of the line and the Panthers held on.
Marking the Tigers' other ex-Panther in Sunia Turuva, left winger Tom Jenkins scored his first hat-trick in a win that keeps Penrith's mid-season resurgence humming.
An away clash against the Warriors is set to prove a litmus test in a fortnight, with Penrith only able to lose four more games this season to finish with a 50 per cent winning record.
Three-time reigning wooden spooners the Tigers head into their bye on a four-game losing streak that threatens to undo their improved start to the season.
After the teams were locked at 10-10 at halftime, Cleary kicked for goal to put Penrith ahead after Luai tackled Penrith's new five-eighth Blaize Talagi.
Jenkins completed his hat-trick, crossing just after Luai was cited for collecting Liam Martin on a kick chase.
But Luai had been involved in everything the Tigers did well in a better first half for Benji Marshall's side.
He first put boot to ball from his non-preferred right foot ahead of Starford To'a's try before again swinging to the right side as the Tigers shifted for Turuva to score.
The 28-year-old was at the centre of another memorable moment early in the second half, flooring opposite man and long-term teammate Cleary in a bone-crunching one-on-one tackle.
In his first game back from a hamstring injury, Jeral Skelton gave the Tigers a sniff with 10 minutes to play as Luai and Adam Doueihi found him on the left wing.
But for a second consecutive week, the Panthers rediscovered their gritty best to hit their second bye in form.
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