Rookie Sam Walker stars as Roosters storm home to sink Sharks

Teenage halfback Sam Walker has put on a performance for the ages to lead the Sydney Roosters to a sensational 26-18 comeback win over Cronulla.

After they trailed 18-4 with just 19 minutes to play, Walker set up two tries and scored one of his own in the space of just seven minutes to leave the Sharks stunned.

Playing in just his second NRL game and at age 18, Walker showed composure well beyond his years.

The result also came with the Roosters playing without third-string hooker Freddy Lussick, leaving rookie Benjamin Marschke to play 63 minutes at dummy-half.

The Sharks also had their own issues, with Wade Graham suffering his second concussion in the space of 15 days and Josh Dugan also failing a HIA.

The Roosters' comeback started through Walker's halves partner Drew Hutchison, who dummied and sliced his way past Chad Townsend with 19 minutes to play.

But even then, a fightback looked unlikely.

Enter Walker.

A perfectly executed cut-out ball from the halfback allowed Daniel Tupou to cross in the corner with 10 minutes to play.

Fittingly the No.7 then levelled the scores himself when he dummied and stepped his way back inside Townsend to cross.

And by the 76th minute the game was wrapped up with a perfect two-man cut-out ball for Brett Morris to score his 11th try of the season.

It came after the halfback had also set up the winger with another cut-out ball earlier in the match, helping equal Michael Cleary's record from 1962 for the most tries inside the first five rounds.

"We expect that (from Walker) because we see it often at training," Roosters coach Trent Robinson said.

"And then the ability to put that from training into the game, usually there's a barrier there called nerves, or fear of the big stage or whatever.

"When that's not there, whatever you do at training you can do on the field and that's been the case so far."

Walker's brilliance came as a cruel blow to the Sharks and under-pressure coach John Morris, who looked poised to claim their biggest scalp in more than 20 months.

After not beating a top-eight side all last year, they were dominant from the opening set when Toby Rudolf broke down field.

They looked as if they'd made a point to target Walker in defence, scoring their first try when they ran it down the last on his edge and their second when Will Kennedy pushed through him.

But even after Townsend and Jesse Ramien combined to help Jack Williams score and give them a 14-point lead just after the break, it was Walker and the Roosters who had the last laugh.

"It was a diabolical last 18 minutes," Morris said.

"They taught us a lesson in how to play 80 minutes. But we shouldn't have been in that situation. We should've won that game of football."