Carlton have suffered a double injury blow with Marc Murphy and Andrew Walker sidelined.

Murphy is set to miss up to three weeks with a calf strain, while Walker has undergone further surgery on the knee that troubled him throughout last season.

Walker was hampered by a knee issue in 14 games last year before he went for a season-ending operation following his side’s round 17 loss to Sydney.

He required another operation after complications arose just before Christmas and as recently as last week remained confident of recovering in time for the Blues’ season opener against Richmond.

But the club announced on Tuesday that the 28-year-old had gone under the surgeon’s knife for a third time.

“It’s unfortunate that Andrew’s had another setback with his knee, however, we are looking forward to him returning to full training soon and he remains in contention for round one,” football manager Andrew McKay said in a club statement.

“Andrew was progressing well in his recovery, but last week pinched his meniscus while training.

“We’re confident this procedure will have him back to his best and he will play an important role for us this year.”

Murphy will miss Carlton’s opening NAB Challenge match against West Coast after experiencing calf tightness during the Blues’ intra-club match last Friday.

“Although this is unfortunate, Marc will still be able to take part in the final two NAB Challenge games to enable him to be fully fit for round one against Richmond,” McKay said.

Exciting forward Troy Menzel suffered a quad injury in the same practice match and must pass a fitness test to play against the Eagles in Mandurah on Friday.

The fresh round of injury concerns comes a week after Matthew Kreuzer fractured the fifth metatarsal in his right foot.

The 25-year-old, who managed just one game last year thanks to a similar injury to the same foot, will be out for up to six weeks.