The Scottish players' union has backed the dropped Steven Pressley and described Hearts' treatment of their captain as "wholly unjustified".
Steven Pressley (left) was dropped against St Mirren
Pressley, having recently criticised his own club, was left out the Hearts team that drew with St Mirren.
Union secretary Fraser Wishart said: "The SPFA condemns in the strongest terms the treatment of Steven Pressley.
"We have for a long time been concerned by the unorthodox managerial and employment practices at the club."
Pressley had appeared to patch up his relationship with the club when he was recalled to the starting line-up last weekend.
But, despite the return from illness of head coach Valdas Ivanauskas, the Scotland defender was again left out the side.
Steven Pressley was 100% mentally and physically available for this game
SPFA secretary Fraser Wishart
BBC Sport understands that Pressley was involved in a row with the team management on Thursday.
Pressley did not train with his Hearts team-mates on Friday, despite being fully fit, having effectively been suspended by the Edinburgh club.
And, following the final whistle at St Mirren Park, Wishart said the union would back Pressley as much as possible.
"Steven Pressley was 100% mentally and physically available for this game," he said.
"He has had - and will continue to enjoy - the full support and backing of the SPFA.
"We, along with our legal team, will offer Steven every assistance to enable him to seek redress via internal football procedures or other means."
Ivanauskas had refused to comment on Pressley's future before kick-off in Paisley.
"If you want to ask me about Steven's situation, it will be tomorrow or Monday," he told BBC Radio Scotland.
Pressley, in late October, voiced his concerns about squad unrest under the regime of club owner Vladimir Romanov.
He was not selected to face Falkirk on 13 November and was an unused substitute against Rangers.
His exclusion led to protests from supporters.
But the rift between fans and Romanov appeared to be healed after a meeting with the Russian businessman and the reinstatement of Pressley.