St Mirren's Homecoming Scottish Cup replay against Motherwell will take place next Thursday and Hearts are insisting their league clash goes ahead on Saturday.
Saints chairman Stewart Gilmour told the Scottish Sun: "It's very disappointing that Hearts wouldn't agree to budge.
"However, I'm a great believer that every dog has its day - and I hope someone will now go ahead and do to Hearts what they have done to us."
Boss Gus MacPherson added: "I'd always considered this to be an unwritten law - a gentleman's agreement, if you like.
"When Sky showed Kilmarnock's replay against Ayr in the last round on a Thursday, Hamilton Accies - who they were due to play the following Saturday - were happy to switch to the Sunday.
"Most clubs would do the decent thing in that situation, but if clubs aren't prepared to help each other then we need a rule change, if only to take the awkwardness out of it.
"I'm sure Hearts will come out with the usual stuff about corporate hospitality and season ticket holders, but most clubs would have moved the game.
"It's not ideal for my players but we have no option and just have to get on with it."