The St George Illawarra Dragons have been reduced to 16 players after just 13 seconds of their traditional ANZAC Day clash against the Sydney Roosters.

Star centre Moses Suli, who has made an excellent start to the season for the Red V, was involved in a nasty collision with Sydney Roosters' enforcer Jared Waerea-Hagreaves and went straight to the ground.

The collision took the form of a head clash, with Waerea-Hargreaves not involved in any foul play during the collision which came at high pace.

He was ruled out almost immediately on the grounds of Category 1 concussion symptoms, having gone to ground and clearly being knocked out.

"He was out before he even hit the ground, so no surprise it's a Category 1. He was very sick and sorry as he walked up the tunnel," Lara Pitt said on Fox Sports' coverage of the game.

The Red V, who will be forced to play the final 79 minutes of the Anzac Day clash against the Roosters in front of a sell-out crowd at Allianz Stadium with 16 men, have moved ex-Melbourne Storm utility Tom Eisenhuth into the centres to take Suli's spot.

The concussion also means that Suli will face the 11-day stand-down period, meaning he won't be able to take on the Cronulla Sharks in Round 9 next Sunday.

NRL Rd 5 - Bulldogs v Roosters
SYDNEY, AUSTRALIA - APRIL 05: Michael Jennings of the Roostersis tackled during the round five NRL match between Canterbury Bulldogs and Sydney Roosters at Accor Stadium on April 05, 2024, in Sydney, Australia. (Photo by Cameron Spencer/Getty Images)

The Sydney Roosters will also play the remainder of the match with 16 men after centre Michael Jennings left the field with a triceps injury.

A late replacement for Daniel Tupou, Jennings set up the Roosters second try, leaping on a loose ball and providing a try assist to Angus Crichton.