The Panthers missed 50 tackles against Brisbane last week, which cost them any chance of victory and they now need results to fall their way in the final three rounds.

Cleary said effort was missing in Brisbane and emphasised their clash against North Queensland this Friday is a must-win if they are to play finals.

Penrith is ninth on the ladder on 10 wins along with eighth-place Cronulla, but they trail the Sharks by 83 in points differential.

"The most disappointing thing (against Brisbane) was the effort areas were the areas we were lacking in," Cleary said.

"You can cop losing if you get beaten, but when you're beating yourselves, it's not up to standard and we've got to turn it around this week.

"That (must-win) is the approach we're taking, but in saying that we've had that the last two weeks.

"We went in with a good preparation (against Brisbane) and knew how big a game it was, but we've now made it a lot harder for ourselves (to play finals)."

Penrith have endured a tumultuous season and managed put together streaks of six losses and seven wins, but Cleary says when the Panthers "get it right", they can match it with any team.

"We've played some good footy in attack but it's been built off the foundation of effort areas and especially our defence," Cleary said.

"You have to build a foundation in defence and if you give them a sniff early, they build confidence off that and we lose confidence.

"It all comes down to effort and attitude, especially in defence. We saw on the weekend, defence wins games - 50 missed tackles isn't good enough.

"Defence is definitely an attitude and our attitude wasn't up to standard.

"If we get it right I'm pretty confident (we'll play finals). If we are to make finals we want to be playing good footy and building into finals to push on from there."

Australian Associated Press