Port Adelaide and the Western Bulldogs have had major injury setbacks, with Zak Butters and Marcus Bontempelli out for at least six weeks.
The Power confirmed on Friday that Butters would be sidelined for six to eight weeks after having knee surgery this week.
Then the Bulldogs dropped a bombshell early in the evening, saying their captain's calf problem was significantly worse than first thought.
Bontempelli suffered a complex calf injury that forced him out of the game in the first quarter of Thursday's pre-season match against Hawthorn.
"While the club was optimistic of a positive result overnight, scans have revealed a complex injury with tendon involvement," Bulldogs head of sports medicine Chris Bell said in a club statement.
"Unfortunately, the structures involved with this particular injury are prone to having recurrent issues so we will need to follow a conservative management timeline to give Marcus the best chance of a successful season."
Bontempelli had told Fox Footy "yeah, I will be alright" after he left the field.
Butters and Bontempelli are two of the league's best players and their extended injury spells are significant setbacks for their clubs' prospects.
Butters, Port's vice-captain and a dual All Australian, had an arthroscopy which the Power said was to "tidy up a loose body found in the knee".
"The injury was likely a result of a heavy knock to the knee, which also caused some bone bruising," a club statement said.
Butters, who has won the past two best-and-fairest awards, was expected to be sidelined for six to eight weeks, the club said.
The dynamic midfielder reported soreness a day after last Friday's match simulation against Adelaide, having suffered a knock to the knee at training in the weeks prior.
Power assistant coach Chad Cornes said he wouldn't be surprised if Butters returned quicker than forecast.
"He'll get on with business and be attacking his rehab as best as anyone would or could," Cornes told reporters.
"He was a little down when he heard the news. But he's a pretty positive guy who wants to get the best out of himself.
"He had the operation yesterday and it went well. He will do everything right in the rehab and might even surprise us and get back a little earlier."
Port's premiership season opens against Collingwood at the MCG on March 15.
The Bulldogs already had a long injury list, with Adam Treloar, Liam Jones and Cody Weightman sidelined.
Key forward Jamarra Ugle-Hagan missed a sizeable part of the pre-season because of personal issues and it is unclear when he will play again.
The only major playing honour to have eluded Bontempelli, 29, is the Brownlow Medal. He has twice been runner-up.
The 2016 Bulldogs premiership player has won their best-and-fairest award six times. He is a six-time All Australian and was named captain of last year's team.
