Kalyn Ponga has returned to fullback with the Knights.

The man with the rugby league world at his feet fears the Knights are letting their season slip through their fingers.

Newcastle superstar Kalyn Ponga said the Knights have run out of second chances after losing four straight and five of their past six, and now face a must-win game against in-form Manly-Warringah at Lottoland on Saturday to revive their fading finals hopes.

Sparked by Ponga and captain Mitchell Pearce and a David Klemmer-led pack that took a backward step against no opponent, the Knights rebounded from a five-game losing streak earlier this season to win six straight and climb from last to fourth.

Having since slipped to ninth, forcing coach Nathan Brown to make four changes for the game against the Sea Eagles, the Knights need to string together a similar sequence to fight their way back into the top eight and secure their first finals berth since 2013.

"We've been in this position at the beginning of the year … and 'Browny' said the same messages back then and the boys reacted really well," Ponga told reporters before training on Wednesday.

"Obviously we went on that run, and I think that's what we need to do now – well, we have to do that now – and we can't dwell and be down on ourselves. We've got to look forward to this week and try hard and believe in ourselves.

"We don't have long, and we don't want to be at the end of the season saying 'what if', or 'we should have done this' or 'we should have done that', so we've just to win, basically."

Ponga said the Knights had responded positively to Brown's selection shake-up but had to take the same attitude to Brookvale on Saturday against the fifth-placed Sea Eagles, who ended Melbourne's nine-game winning streak at AAMI Park last Saturday.

"… We'll see how they go, but the boys that are coming in, they want to be there and they want to defend and do the jersey proud, so that's the main thing for me," he said.

"A lot of the boys on the weekend did have effort, but I don't think we executed or were smart about the way we went about it.

"It was obviously our defence that let us down because 26 points is enough to win a game of footy. I just don't think we paid enough attention to the wrestle and the finer details …

"If you want to win a tackle, you'll win it, and I don't think we've had enough attention to detail in that area over the last few weeks."

The Queensland Origin fullback was sin-binned in the final minutes of Newcastle's 28-26 loss to Wests Tigers last Friday night for making contact with Michael Chee-Kam's head in a contest for a grubber kick, but the NRL match review committee found he had no case to answer.

Though there was outrage from some commentators, and diehard Knights fans, Ponga had no issue with the original decision, did not feel particularly vindicated by the outcome, and has no plans to change the way he plays.

"I don't know what they wanted me to do … I was competing for the footy, and that's what you do in this sport," he explained.

"It was unfortunate that it happened, and I felt really bad that I did make contact with his head, but there was no intention in it. It was purely just an accident. I'm going to compete for the footy as much as I can, and I just hope it doesn't happen that way again.

"Like I said after the game, I didn't really care what happened [to me], I was very concerned with how Chee-Kam was. Personally, I was just competing for the ball and once I dove, I had to brace, and it was just unfortunate that I hit his head.

"I'm glad that I think he saw it that way as well, that I was only competing, then the judiciary saw it that way as well. I didn't feel like I should have been charged, or shouldn't have been.

"I knew it was an accident."