Penrith have sprung the first upset of the NRL season, storming home to defeat reigning premiers the Sydney Roosters 20-14.

The Roosters led 12-0 early and were up by six points with 17 minutes to go on Saturday night when Stephen Crichton set up a grandstand finish with a try off his first touch.

Playing in just the fifth match of his career, Crichton had only just run on the field for fullback Caleb Aekins when Josh Mansour found space down the left edge.

But the 19-year-old made an immediate impact by latching onto Mansour’s in-field kick to ignite the Panthers Stadium crowd of 10,160.

Crichton’s injection proved to be the turning point, with Nathan Cleary running to the line and offloading for Viliame Kikau to give the Panthers the lead.

Kikau had earlier given Penrith fans a scare when he left the field with what appeared to be a serious shoulder injury, only to return in the second half.

The Roosters had an opportunity late to steal a season-opening win, however the home side held on to hand the visitors their first loss since round 25 last year.

Already without rested co-captain Boyd Cordner, the Roosters also lost Angus Crichton before the game due to a chest infection.

But it mattered little as the visitors flew out in sixth gear, opening with a penalty goal in the second minute before Mitchell Aubusson crossed soon after.

Registering 19 of the first 23 plays of the match, only a marginally forward pass by James Tedesco prevented them going further ahead five minutes later.

A blowout loomed when Sio Siua Taukeiaho pounced on a grubber in the 20th minute, but the Panthers halved the deficit at the break with a Brent Naden try.

Both teams traded penalty goals in the second half but it wasn’t until Crichton’s late-game heroics that the home side had a whiff of victory.

The loss for the Roosters was further soured by a concussion to Matt Ikuvalu, while Sitili Tupouniua limped off late with a suspected knee injury.