Motherwell's home match against Celtic on 6 January has been postponed following the death of Phil O'Donnell.
The Well skipper, 35, died shortly after suffering a suspected seizure against Dundee United on Saturday.
Motherwell's SPL game with Hibernian, scheduled for Wednesday, has already been called off, as has Gretna's match against St Mirren on the same day.
SPL chairman Lex Gold said O'Donnell's family had requested that the game against Celtic should not take place.
"We understand from Phil's family that they would appreciate it if the Motherwell v Celtic game could be postponed," he said.
"Both clubs are happy to meet the request and we have called the game off."
"To contemplate going on a training ground, never mind a football ground at this moment is impossible"
Gretna are currently tenants at Motherwell's Fir Park ground because their Raydale Park does not meet SPL standards.
Gold added: "It is clear that Fir Park has become a place of homage for many fans of Phil.
"Sensitive to this, Gretna and St Mirren have agreed with the SPL that the game should be postponed.
"The four other games on Wednesday will proceed as planned with the clubs being invited to honour Phil's memory before the start of those games."
Motherwell manager Mark McGhee backed the decision to cancel his team's next two fixtures.
"Our players in particular are so close," he said.
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"It has been well-documented how few we have used this season and that is something that brings them together. There is a unity about them.
"Phil was a figurehead to them. He was not just any player, he was the focal point and the senior member of the squad.
"For any of us to contemplate going on a training ground, never mind a football ground, at this moment is impossible.
"We are all going to need time to get back to work."
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