Chris Chester lashed out at a "disgraceful call" by the officials to allow Liam Marshall's hat-trick try in Wigan's tense 24-16 win at Wakefield.
The score was locked 12-12 in the second-half when the winger defused a kick, rushed to take a quick tap restart and blazed through to score.
But Trinity boss Chester was angry referee Scott Mikalauskas allowed the try to stand, saying Marshall was "six or seven metres" away from the middle of the 20m line where players are supposed to tap the ball.
"I can cop a player being a metre away from the centre, but when you're talking six or seven metres... I don't know how many officials we have, but they let Liam Marshall tap it where he wants," said Chester.
"That's a disgraceful call. A disgraceful call. And one you shouldn't get wrong, there's a line there."
He praised his players for going toe-to-toe with the Warriors in a tense, if error-littered, match which was only settled by Sam Powell's try in the last minute.
"We rattled them in the first 40 minutes," said Chester. "We got beat but the effort was fantastic. I couldn't be more proud.
"Wigan are the best team in the competition at the moment and we more than matched them.
"Credit to Wigan, they were very good, they know they've been in a match."
Informed of Chester's remarks, Lam said he hadn't watched it back and - perhaps nodding to the controversy involving Saints chairman Eamonn McManus - said: "I want to stay positive about the referees today."
Chris Annakin (groin) and Bill Tupou (pectoral) suffered injuries for Wakefield which are likely to rule them out of their final two matches.