The Australian Kangaroos' first full-training session ahead of their World Cup opener against Fiji hasn't gone to plan, with talented Melbourne Storm dummy-half Harry Grant causing some anxiety after an injury scare.

Grant collided heavily with the goalpost during the session and took a considerable time to return to his feet, clutching his ribs when he finally got back up.

“I was chasing Reuben (Cotter) down the line and cleaned the post up,” Grant told 9News after the session.

“I'm not too bad (now), I got through the session pretty good – just a little bit of pain at the start.”

Though the Storm No.9 completed the session with ice on the affected area, he was adamant that the incident wouldn't stop him from making his Kangaroos debut. Grant has been named on the bench in jersey No.20 for the opening game this weekend.

“Every kid dreams of playing for Australia,” Grant said.

“I remember the World Cups back in the day, getting up, setting alarms at all hours of the night to get up and watch the games. To be here, doing it now is pretty special.”

Grant is one of seven Kangaroos players who'll make their Test debut in the opening game, though it remains to be seen if Meninga will give Grant an opportunity at the starting No.9 role later in the tournament – a role that will be played by Ben Hunt to begin.