Portland's Tommy Haylock hyper-extended his knee in the Tigers' elimination final win against Warrnambool.

An ultrasound confirmed serious damage which will rule him out of the club's first semi-final against South Warrnambool at Cobden Recreation Reserve on Sunday.

"It didn't look good. He had a bit of pain and swelling," Portland coach Jarrod Holt said.

"He's not exactly sure what happened. He said he remembered someone falling across him in a contest.

"He looked down at his knee and it didn't look right, hobbled off and iced it straight away."

Holt said Haylock, who will have an MRI, had damaged medial ligaments.

Haylock has played 15 senior games for the Tigers this season.

"Tom's really versatile for us; he's a hard worker and honest player," Holt said.

"We'll miss him but there's five or six other guys I'd be happy to play in the side as well, probably different players to Tom. Whoever we bring in will have an impact for us."

NAB League player Jamieson Ballantyne, who has battled a foot injury this season, won't be available to play for his home club.

"He made a decision through some advice he had he was best off not to play and we respect that," Holt said.

"His commitment when he comes back is fantastic. He loves it and he's got some really close mates at the club.

"Sometimes with players who are back and forth with the Rebels and VFL programs are not always fully invested but I could never question Jamo; he's fully invested, he loves it."

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