King played 78 games for the Knights before joining Melbourne at the start of this season and said he would remain mates with a host of Newcastle players long after their careers are finished.

While Melbourne are flying high in second spot, Newcastle are struggling after five consecutive losses.

King clearly harbours no ill-feeling towards his old club but said he has a job to do at McDonald Jones Stadium on Sunday.

"I want to see success for them as well, and it hurts me to see them going through troubling times," he told the Newcastle Herald. "But I also know the calibre of the squad there and how good some of those players are.

"I know that they're a competitive team and they're capable of great things once everything clicks.

"So I do feel sorry for the them and I want the club to do well. I don't enjoy seeing them losing that many games in a row, but I also believe good footy is just around the corner for them.

"It'll be a good fight but hopefully Melbourne walk away with the victory."

The 27-year-old said it would be strange running onto his former home ground as a member of the visiting team but he had a "bit of a dress rehearsal" when Melbourne played the Knights in a pre-season trial.

"Some of those guys, they're my best mates not just in rugby league, but in life," he said. "Our friendships go well beyond footy. I still speak to them a lot, although not as much this week.

"I just have to prepare like I do for any other game and worry about what I can control. I know what those boys are like, and they're very competitive, so it'll be a good battle out there."

Mainly a bench player at Newcastle, King will start in his eighth straight game for Melbourne.

"I would never have imagined it turning out like it has," he said.

"It's crazy to me that I'm playing for the Melbourne Storm, how far I've come and where I've come from.

"I'm just a young fella from Singleton and somehow I've ended up here.

"To have started in every game this year, and be playing considerable minutes, I could never have picked this happening in my wildest imagination.

"I'm just so happy down here and loving my footy."

King said he was almost in disbelief as Melbourne slaughtered the Warriors 70-10 on Monday night.

"It was incredible," King said. "I've never been on that side of a score, that's for sure.

"In my early days at the Knights we had a few big scores like that put on us.

"I went back out in the second half, and it seemed like I wasn't making any runs or tackles. I was just walking up the field almost in awe of those blokes."

He said the quality of his teammates had helped him settle quickly into Melbourne's starting pack.

"I've never played a fancy brand of footy, but what I'm doing is all they want from me," he said.

"They don't expect me to do any more than I'm doing. They don't expect me to be breaking heaps of tackles and scoring tries."

Knights coach Adam O'Brien said he was not surprised to see King's progress.

"That's what Kingy does," he said. "He gets his job done, so he seems to be a good fit for them there at the moment."

O'Brien said he had no regrets about the departure of King, who accepted a two-year deal with Melbourne midway through last season.

"Josh is a great clubman," he said. "If he was to leave him, I think that would be a good fit for him going down there.

"I don't like losing anyone, but you can't keep them all.

"There's always ripple effects. You keep one, you lose another.

"It's about trying to get the balance of your squad right. We've got some pretty big middles here in the Saf boys and Klem, so we had a few guys in front of him.

"I think Melbourne, their situation with Tui [Kamikamica] not being available and [Christian] Welch being out, has probably helped a bit, too."