Jonny Lomax is to become the fourth teenager to make his Super League debut for St Helens this year.

The 19-year-old academy product, whose specialist positions are hooker and half-back, will deputise at full-back for Paul Wellens against Wakefield at Belle Vue on Friday.

Wellens, one of a trio of internationals ruled out by injury, has a chronic knee problem but is hoping to delay surgery until after the busy Easter period.

"We're trying to nurse him through," said St Helens coach Mick Potter, who has also ruled out scrum-half Sean Long and hooker James Roby with leg and rib injuries respectively.

"It's another opportunity for the kids. Jonny had a knee re-construction last year and we've eased him back at full-back with the reserves.

"His opportunity has probably come earlier than expected but he's a good young kid and he will acquit himself well."

Potter has already given debuts to 19-year-olds Andrew Dixon, Tom Armstrong and Matty Ashurst so far this season.

Another teenager, Gary Wheeler, will switch to scrum-half alongside Leon Pryce, with former New Zealand international Francis Meli taking over on the wing for his first match of the season after being stranded in Auckland by visa problems.

Wheeler said: "I don't think I've played scrum-half but it's not much different to stand-off. Leon will be the main person to control the team, I'll be there to help."

Saints also have prop Tony Puleta back from injury and hope that England front-rower Maurie Fa'asavalu recovers in time from the knock he took to his face in last Friday's 26-18 win over Leeds.

Potter criticised the Rugby Football League's match review panel for their decision not to charge Leeds prop Ryan Bailey over the incident which led to Fa'asavalu leaving the field badly dazed and with blood pouring from his broken nose.

The panel ruled that Fa'asavalu dipped into the tackle and that there was no intent by Bailey.

"Maurie has had to go to the hospital for a second time this morning for x-rays because his nose has not yet congealed," said Potter on Wednesday.

"Apparently you are allowed to hit blokes 'accidentally' on the head. I think it sets a dangerous precedent. It's a real issue for me that you can get away with that.

"I understand it's a contact sport but I'm a little disappointed that he wasn't charged at least with a careless or reckless tackle."

Fa'asavalu will have to pass a "head test" before he can face the Wildcats.

Potter expects Roby and Wellens to return for the eagerly-awaited Challenge Cup tie at Leeds on Sunday week but Long remains a doubt.