The home side were without an 18th man after losing forward Frankie Halton and full-back Bailey Hodgson, while Cas lost centre Krystian Mapapalangi to a quad injury in the warm-up, with Ravalawa drafted in.
Tigers thought they had scored with their opening attack through Jason Qareqare’s finish inside the corner post, but a video review ruled the ball had brushed the touchline in the grounding.
Seconds later, Leigh rubbed salt in the wound as Armstrong’s chipped kick infield bounced kindly for Lam to finish the move he had started.
The visitors’ missing cutting edge was punished again when Lam’s dummy created space for Jack Hughes to dart through and give Armstrong a clear run to the line.
But Tigers deservedly replied as Hall came off the bench to chase down Daejarn Asi’s deft grubber kick.
Leigh struggled for momentum, conceding a string of penalties deep inside their own territory under mounting pressure.
And the visitors made their territory and possession pay just before half-time as Ravalawa barged over in the right corner and Asi’s touchline conversion went over off a post.
But hopes of a first Cas win over Leigh since 2021 failed to materialise after the break as the Leopards extended their unbeaten run in the fixture to nine matches.
The home side needed just four second-half minutes to nudge back in front when Hanley turned on the afterburners to burst past the cover defence and touch down Lam’s grubber.
Lam was involved again as another dummy gave Armstrong space on the left edge to sidestep the last man and cross.
The visitors were reduced to 12 when Louis Senior was harshly sin-binned for a high tackle on Armstrong who appeared to lose his footing and fall into the Cas centre.
But the visitors kept coming and, after Qareqare had a second score overturned for Alex Mellor’s adjudged obstruction, Laulu-Togaga’e skipped through a gap to set up a tense final five minutes.
Leigh: O’Brien, Armstrong, Senior, Hanley, Charnley, Cook, Lam, Davis, Horne, Brogan, Hughes, Trout, Liu.
Interchanges: McNamara, Brown, Ipape, Vaalepu.
Castleford: Laulu-Togaga’e, Valemei, Senior, Ravalawa, Qareqare, Asi, Windley, Stimson, Golding, Lawler, Lane, Mellor, Brown.
Interchanges: Atoni, Ashworth, Hall, Robb.
Sin-bin: Senior (68).
Referee: Liam Rush.
