Hearts captain Steven Pressley has held talks with players' union boss Fraser Wishart amid doubts over his future.
Pressley spoke out about unrest in the dressing room
The Tynecastle club insist the defender, 33, chose not to play against Falkirk on Monday, having declared himself mentally unfit.
Sporting director Alex Koslovski told Hearts World: "Captaincy rumours unsettled him - he asked not to be selected due to his state of mind."
Pressley trained on his own on Tuesday and refused to comment.
Last month, Pressley spoke publicly of "significant unrest" at the club, following the departure of head coach Valdas Ivanauskas on sick leave.
And the "rumours" that Koslovski mentioned are thought to relate to an alleged plot inside the club to strip Pressley of the captain's armband.
"Of course it's a concern," goalkeeper Craig Gordon told BBC Sport after Monday's 1-1 draw at Falkirk. "It's something that we need to sort out."
While Hearts officials would not comment, Gordon did talk to BBC Sport but would not reveal the details of Pressley's shock omission.
We are going to give everything we have to bring success to this club
"I have spoken to Steven and he wished the boys all the best for the game," he said.
"He still wanted us to get the result and do the best we could for everyone here.
"He did not play tonight but, hopefully, he will come back into the reckoning as soon as possible."
The Edinburgh side have gone off the boil in recent weeks and have not won a game since they hammered Dundee United 4-0 on 1 October.
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Fellow Scotland international Paul Hartley, who flanked Pressley when he read a statement outlining the players' unrest, was dropped to the bench for the Falkirk match.
And Hartley was not introduced until injury time in a match that saw several Hearts players under-perform.
Gordon was quick to quash the rumour that he and Hartley had offered not to play in support of Pressley.
"No chance," he told BBC Sport. "We are not walking out on the club and especially the fans who have been fantastic through all of this.
"There is absolutely no way that will happen from anyone in this squad. We are going to give everything we have to bring success to this club."
Pressley has been at Tynecastle since 1998 and signed a two-year contract extension in March 2005.