Coach Jamie Joseph admits the yellow card picked up by Ma'a Nonu was a key in the side's loss to the Blues last night.
Nonu was yellow-carded after a shoulder charge on Piri Weepu, and the side conceded 12 points while he was off the field.
Joseph said it was not a malicious hit from Nonu but agreed it was a momentum changer in the match.
''We have had that happen to us in the last three matches and these games are tight, the competition is tough. You can't afford to play with 14 men,'' he said.
''That is a lesson we are not learning and we are playing dearly for it each week.''
He said the side again showed a lack of composure at key times.
''We did pretty well in the scrum, pretty good in the lineout. So there is not an inability to get the ball. But I think patience at times, for lots of different reasons, was not there. We are trying to rush things too much.
''That is most probably pressure being put on yourself. When you are losing you have to try as hard as possible not to put pressure on yourself.''
The side was hot on attack at the start of the second half for a good period but could not turn that possession into points.
Highlanders captain Andrew Hore says his side is still making too many basic errors and need to start realising why they play the game.
''We just need to take a deep breath, and remembering what you are doing and why you are playing footy out there. We need to get out there and have some personal pride in what you are doing. Once we get that sorted out, all 15 guys start going the same way, the Highlanders may get a win.
''At the moment, we are looking left and right, instead of straight ahead in the mirror. Until we get that sorted out, we are going to be under the pump
''We just need to get the basics. And you can't get more basic than just trying to hang on to the ball . . . we are giving it away too easily.
''It is bloody frustrating. But I could be home digging fence posts for the old man, earning a few dollars instead of a few grand. So I think a few of the rest of the team needs to look at life like that.''
Winger Buxton Popoali'i was taken to hospital last night with concerns over his neck.
Joseph said he was concerned about the winger's health after he had been knocked out by a high blow from opposition winger George Moala.
He lay on the ground for more than five minutes before leaving the field on a stretcher, as the Highlanders injury list blew out.
Lima Sopoaga rolled his ankle and could not walk, Jamie Mackintosh also could not continue playing in the second half, after he rolled his ankle, and young centre Jason Emery took a blow to the ribs from a late hit in the first half.