A "captain's challenge" will be trialled in the NRL for the first time this weekend.

The initiative will be used in Saturday's match between St George Illawarra and Newcastle at Jubilee Oval as well as upcoming NYC finals.

Under the trial rules, each captain will be allowed to challenge the referee's decision in relation to tries only.

The referee will be required to make a decision on the field and it will only be reviewed by the bunker if a challenge is made.

Each team will be allowed one incorrect challenge per half but there will be no limit on how many times a captain can contest a ruling by the match officials if he continues to be proven right.

An additional challenge will be allowed in the final 5 minutes of the game and in golden point.

CEO Todd Greenberg said the NRL had been considering a captain's challenge system for several years but did not previously have the technology to be confident the correct decision would be delivered.

"However, the bunker gives us the opportunity to trial the captain's challenge with state of the art technology to help determine whether a try has been scored," Mr Greenberg said.

"We will assess the trial to determine if there is scope to use the captain’s challenge more widely in the future."

In the Dragons v Knights trial, the bunker will continue to be used for 40/20 rulings, goal line drop outs and 20 metre restarts, reportable foul play, double knock-on rulings and to determine which team touched the ball last before going over the touchline.

In the NYC Finals, the bunker will only be used to determine whether a challenge to a try scoring decision is valid.

The trial of the Captain's Challenge has been endorsed by the Competition Committee and the ARL Commission.

Head of Football, Brian Canavan thanked the Dragons and Knights for agreeing to trial the captain's challenge during a Telstra Premiership match.

"This will give us a chance to evaluate the captain’s challenge in a live NRL game where teams are still playing for two competition points," he said.

How the Captain's Challenge will work:

- Can only be used to challenge a try or no-try ruling

- Captains will have 20 seconds following a try/no-try decision to challenge the decision.

- No replays either at normal speed or in slow motion, will be shown on a big screen at the ground until the time allowed for requesting of a captain's challenge has elapsed.

- A captain may request a review of any try/point-scoring decision made by an on-field official in relation to: groundings, knock-ons, obstruction, double movement, offside, touchline /touch-in-goal/dead-in-goal, tackle in the air, steals involving two or more defenders, foul play, as well as goals and field goals.