Looking to shake off news of Stefano Utoikamanu's impending exit, Wests trailed by only six points when an airborne Olam hit Heilum Luki high during the second half at Leichhardt Oval on Thursday night.
The centre's dismissal in the 49th minute opened the door for top-four hopefuls North Queensland, who threatened to botch certain victory as Wests provided late resistance.
Justin Olam reacts after being sent off. (Mark Evans/AAP PHOTOS)
After fulltime, Tigers coach Benji Marshall watched his words as he reflected on Olam's game-defining hit, which is likely to land him a suspension.
"I've got a group of guys in there who are feeling pretty down about it," Marshall said.
"The easy thing for me to do would be to come out and say that it was a bad decision and that (the referee) got it wrong, and that a sin-bin probably would've sufficed.
"But I'm not going to say that."
The Cowboys conceded three tries with the numerical advantage, with only Kyle Feldt's four-pointer in the final minutes putting paid to the Tigers' comeback.
"The send-off happened, we scored a couple of quick tries and went to sleep. I'm a little disappointed with some periods there when they were down to 12 men," said Cowboys coach Todd Payten.
The home crowd gave Olam a standing ovation as he was sent from the pitch, not long after some had booed Utoikamanu during the team announcement and his first hit-up of the night.
The star prop's decision to leave at the season's end is a big blow to long-term plans.
But it's the immediate future that is of most pressing concern for the 17th-placed Tigers, who were hoping to parlay a return to their spiritual home into a drought-busting win.
Instead, they were set further adrift at the bottom of the ladder with a sixth-straight loss despite teenager Lachie Galvin again proving capable of running his team's attack and second-rower Samuela Fainu nabbing his first career double.
Fainu's second try came after Solomon Alaimalo and Solomona Faataape also crossed despite the Tigers being down a man.
Marshall was pleased with his side's ability to hang tough.
"As a coaching staff, we asked for 80 minutes competing tonight and they gave it," he said.
"Some things were out of our hands, but the fight they showed, as a coach (I'm) just really proud."
Valentine Holmes would have been forgiven for reconsidering his request to test the market after six of the Cowboys' eight tries came down his left edge.
The big-money centre threw the last pass for Murray Taulagi's second try as the Cowboys exploited the Tigers for failing to adapt to the restructure prompted by Latu Fainu's head knock.
With the numerical advantage, he got his name on the score sheet, and threw a ball down the short-side that confirmed Taulagi's hat-trick.
Murray Taulagi scores one of his three tries for the Cowboys. (Mark Evans/AAP PHOTOS)
But Payten still felt Holmes fell victim to the Cowboys' lapses in focus during the second half.
"After the send-off, he was one of a few players that didn't concentrate hard enough," Payten said.
A mid-game pectoral injury threw Jake Granville's NRL future into doubt.
The premiership-winning Cowboys veteran is out of contract at the end of this season and will be 36 by the start of the next one.
"Things aren't looking great. It's a strained pec, at least. He'll be missing for a while," Payten said.
"He'll go for a scan. Fingers crossed we get some good news."
