First Glasgow has launched a legal challenge to a ballot by trade union Unite, which is due to close today.
Members are expected to turn down a 1.2% pay rise in each of the next two years. An initial offer of a 0.5% increase was rejected by 143 votes to three following an earlier ballot.
The Evening Times understands First Glasgow has instructed multinational law firm Eversheds to challenge the most recent ballot.
The legal bid is believed to be based on a dispute over the official name of the bus firm.
A source close to the union said: "The ballot described the company as First Glasgow Limited, but they say the company is actually known as First Glasgow No 1 Limited and First Glasgow No 2 Limited.
"It's shaky stuff but these things have interfered with industrial action before."
The lawyers are also claiming that the postal ballot period was too short, according to a union source.
The bold move could force Unite to rerun the ballot and see off the threat of walk outs during the Commonwealth Games, which are due to begin in a fortnight.
The trade union source slammed First Glasgow over the legal challenge which is expected to cost thousands of pounds.
He said: "You have to question how much money First are paying this law firm to break this strike ballot.
"It's sad that a workforce with a history of co-operation to deliver decent bus services for the people of Glasgow are being attacked by their employer for seeking a modest pay increase after years of real-term cuts.
"First would be better channelling their energies and finances into negotiations to reach a modest pay deal that meets the cost of living for hundreds of Glasgow based workers."
The bus operator announced last week that it has invested £20m in 109 new vehicles that will shuttle visitors between games events.
The union source added: "It would seem that First - content to showcase their investment in new buses and executive bonuses - would rather suppress their workers than engage with them."
A spokesman for First confirmed a legal challenge has begun but declined to comment further.