WESTERN Bulldogs skipper Brad Johnson will miss the start of the premiership season after suffering tightness in his troublesome calf.

Johnson, 33, suffered a blow to the muscle five weeks ago that caused bleeding into the achilles area.

The injury has been slow to heal, but he had been in the frame for selection in Saturday's NAB Cup grand final side before the setback.

"He trained yesterday and when he came in this morning it was just a bit tight," coach Rodney Eade explained on Wednesday.

"There was no real pain with it, but it was always going to be right on the edge whether he played on it or not so we're just going to err on the side of caution."

Eade is confident Johnson will resume running by the end of the week, but the interruption to his pre-season will see him miss round one when he was due to play his 350th AFL game against Collingwood at Etihad Stadium.

"It's a long year and we want to do the right thing by him," Eade continued.

"He understands that too, so we'll give him a lot of conditioning over the next few weeks and hopefully he's back for round two or maybe round three."

Eade forecast a short stint with VFL affiliate Williamstown for Johnson, possibly starting as early as next week, in order to build his match fitness for the season proper. 

Daniel Giansiracusa will captain the side in Johnson's absence.

"[But] there's nothing to read into that for the future as far as [him being] an 'heir apparent' if that's the right phrase," the coach said.

"If Brad misses again during the season it doesn’t necessarily mean that Daniel will be captain for that period.

"But for this period whether it's two, three or four games Daniel will be captain."

Eade cited Giansiracusa's good form, excellent application to his training and the positive influence he exerts on the group as the key factors in him getting the nod ahead of several other strong candidates.

Giansiracusa hasn't captained a side on a full-time basis since his days as a Williamstown junior and he was delighted to be chosen to lead the side in place of Johnson.

"Obviously I'm just warming his seat, but it's a good honour and I'm looking forward to Saturday night," Giansiracusa said.

"It's something that I've aspired to. I've been in the leadership group for four or five years now and it's something that I'm proud of, but there are another eight or so guys who could have done it in our leadership group.

"Johnno could go until he's 40 so I'm definitely just warming his seat. He's the skipper, we'd love him out there and he's obviously a vital player for us, but knowing the way he goes about it, he's doing everything possible to get himself right."

Brad Johnson is a $431,400 forward in this year's Toyota AFL Dream Team.