Carlton coach Brett Ratten says Jarrad Waite is crucial to the AFL club’s premiership hopes and the key forward’s continued absence with a back injury is becoming a serious issue for the Blues.

Waite, who was rested from the round-six clash with Greater Western Sydney with a hip complaint, played the following week against St Kilda but has since been troubled by a back injury.

The aggressive big man will miss a third consecutive game after Ratten ruled Waite out of Carlton’s clash with 15th-placed Port Adelaide at AAMI Stadium on Saturday night.

“It’s becoming serious because of the length (of time) that he’s out for,” Ratten told reporters on Tuesday.

Waite had hip surgery last year and missed Carlton’s semi-final exit at the hands of West Coast in Perth in September.

“It’s something that has probably frustrated him. He has tried to set his season up with a great pre-season,” Ratten said.

“He got himself into a great position to play well.

“We gave him an opportunity to freshen up so he could get through and maintain a full season of football and now he’s had this interruption as well.

“Hopefully he gets up for the Cats (on June 8).

“But he has missed a bit of footy so that will become the next conversation, where do we play him if he is right?

“We don’t know when he’s going to be right at the moment. We’re really mindful of getting him back.

“When you’re trying to get to the pointy end of the season, getting your best players and your talent out on the field is so critical.”

Ratten was pleased with the efforts of Aaron Joseph, Brock McLean and two-game teenager Josh Bootsma in the absence of players such as defender Jeremy Laidler and midfielders Marc Murphy and Andrew Carrazzo.

The Blues coach said Lachie Henderson (hip tightness) was unlikely to play this week, while fellow defender Chris Yarran (toe) would be fit to play for the sixth-placed Blues.

Nick Duigan (calf) will miss another week while Andrew Collins (jarred knee) will face a fitness test.