Melbourne coach Craig Bellamy has warned his under-performing players the loyalty factor can only stretch so far as they try to snap their five-game NRL losing streak.

The Storm host lowly Penrith at AAMI Park on Saturday, looking to arrest their fall from the top of the ladder.

Bellamy made only one change to the line-up, bringing Gareth Widdop back in at five-eighth to link with Cooper Cronk, with the Storm finally fielding their top halves combination for the first time since the second State of Origin match.

Star fullback Billy Slater will be back for his second hitout since returning from six rounds sidelined with a knee injury.

But the coach, who admitted he wasn’t sleeping well as he dealt with the “new experience” of five losses, said changes were ahead if players didn’t deliver.

While injuries to players such as Matt Duffie (shoulder) and Justin O’Neill (groin) have limited his replacement options, under 20s winger Mahe Fonua is knocking on the door of a NRL debut with his try-scoring feats in the NSW Cup.

“There’s a loyalty factor there … but there are some guys who need to perform better or we will have to make some changes,” said Bellamy on Wednesday.

“Having said that, these players have done a wonderful job for us earlier in the year and we’ll give them the chance to find that again.

“Slowly but surely, that time’s running out but you’d like to think we’ll find some consistency in the things we need to do and hopefully that will be this week.”

Bellamy said he had been tempted but didn’t want to throw a young player in who wasn’t really ready to make his NRL debut because it would be a “backward step” for that player.

The veteran coach said he couldn’t remember experiencing such a losing streak, even back to his days as a player, and said it was a frustrating time.

“The one thing we’ve always been reasonably good at here is being pretty consistent and that’s the thing that’s really frustrating me,” he said.

“We can do some really good things for periods in a game and then, for 23 minutes, we drop off and we’re paying the price.

“That’s what happens. When you’re not playing well and you’re not playing with that consistency, you seem to pay a lot more dearly for your mistakes.”