A try on debut for Alex Johnston has raised further doubts about Nathan Merritt's place in the Rabbitohs side.

Johnston shines as Merritt waits

Club icon Nathan Merritt is facing an extended period in the lower grades following an eye-catching debut from 19-year-old winger Alex Johnston in South Sydney's pulsating 28-26 win over Brisbane on Friday night.

Amidst a powerful surge of red and green to open proceedings Johnston was able to cross for his first try in the top grade in the opening 10 minutes of the game and showed enough in the following 70 minutes to justify coach Michael Maguire's shock selection.

Merritt will turn out for North Sydney in the NSW Cup on Sunday and with a City Origin spot unlikely next Friday night in Dubbo, the 30-year-old will again be asked to play reserve grade for the Bears against Canterbury next Saturday.

It's a sharp fall from grace for the man who represented New South Wales 12 months ago and just two weeks ago became the foundation club's greatest ever tryscorer. Unless Maguire decides to punish Bryson Goodwin for his impulsive quick tap that ultimately earned the match-winning penalty, Merritt's stint in the lower grades may extend to the start of the Origin period.

With a frame that has filled out in his first full off-season over the summer, Johnston looked immediately at home in his NRL debut, producing some aerial acrobatics for his maiden try, coming in to take some strong charges from dummy-half and stretching the Broncos defence with a searching run on the right in the second half.

"He's been showing that for quite a while and I've been looking for an opportunity to give him a chance and it just came about this week and he definitely performed really well," Maguire said.

"To score that first try and then to come up with that effort [in the second half] where he went to the outside and got himself down, that's a big play, a massive play.

"It's probably the worst part of the job, having to tell a player that works as hard as Nathan has been to have to go back [to reserve grade] and give someone else an opportunity but I was really pleased for young 'AJ'. He's been working hard and he deserves his opportunity.

"I know Nathan is a very, very motivated kid and he's going to fight and do everything possible to get himself back to get an opportunity again."

Coming off a one-point loss to the Bulldogs that left as much physical bruising as mental scarring, South Sydney raced out of the blocks in front of 44,122 at Suncorp Stadium and had built a 14-0 in the space of 14 minutes, Greg Inglis's front-runner for try of the year capping an extraordinary opening period.

But in an eerily similar scenario to last year's Preliminary Final against Manly, the Rabbitohs handed possession over to the Broncos and were unable to get it back until the home side had posted three tries and taken an unlikely 16-14 advantage into half-time.

The brutal opening salvo was indicative of the type of football that the Rabbitohs have displayed for the past two seasons but Maguire rejected the suggestion that the Representative Round is poorly timed for his team, welcoming the chance to rest some battered bodies.

"We've got a bit of a walking wounded group at the moment and it gives us a chance to really freshen up over this next two weeks and get ourselves back and look at the good things that we've been doing over this last month and take them into the next part of the season," said Maguire, who may have Tom Burgess available for the Round 9 clash with the Titans on the Gold Coast.

"John [Sutton], to be honest, probably shouldn't have played today. He was probably nearly going to be ruled out yesterday with his leg, he had a slight strain, but it's things like that this team is building itself on.

"That was a ferocious game with different parts where we were in control and they were in control and then it really came down to a bit of a dogfight at the end there of trying to find a way to win it. 

"Obviously we learned a few lessons from last week and I was really pleased to see the players come out the right side this week."

Having let a lead slip against the Bulldogs last week, captain John Sutton said it was a positive sign to fight back and secure the two points and perhaps lay to rest some of the demons from the loss to Manly at the end of 2013.

"It was good to bounce back but we need to cut those periods out of our game," Sutton said of the period where Brisbane enjoyed 10 consecutive sets in the latter stages of the first half. 

"We just have to keep trying to play for that full 80. We didn't do it tonight so we've got heaps of work to do but just glad to get the win.

"You give Brisbane too much ball and they'll put points on you so it was good to just come out the other side."