Labour have won two local council by-election victories that were held on Thursday.
The vacancies in Glasgow and North Lanarkshire were created by Nationalist councillors standing down after becoming MSPs.
The Scottish Parliament's Labour leader Iain Gray said it a "stunning" result for his party.
He said: "It is also a personal humiliation for Alex Salmond as two of the seats won were vacated by his SNP MSPs standing down from their dual council roles.
"Unlike their boss they gave up their dual mandate and voters replaced them with Labour."
In Glasgow's Drumchapel-Anniesland ward, where Bill Kidd had been councillor, Labour beat the SNP by 2,584 to 1,509 in first-preference votes.
In North Lanarkshire's Coatbridge North and Glenboig ward, Labour beat the SNP by 1,529 to 1,254 in first preferences after John Wilson stepped down.
In both cases, counting went to subsequent rounds under the Single Transferable Vote (STV) system.
The SNP said the Coatbridge result saw a 5% swing from Labour to the Nationalists, and said the final result came only after a disputed recount, with Labour winning by a margin of 63 votes.
They said the Glasgow result saw a swing of nearly 10% from Labour to the SNP, saying: "The SNP vote has increased substantially while Labour's is collapsing."
The SNP also claimed the two results combined represented a 7.8% swing from Labour to the Nationalists compared with 2007.
