The court filings are part of an increasingly personal spat pitting two of the tech world's titans against each other. Google and Microsoft compete in a number of areas including Internet search, and are now locking horns over Lee, who was vice president at Microsoft and founded the software giant's China research lab .
Microsft sued Google and Lee last week in a Washington state court, claiming Lee was breaking a non-compete promise in his employment agreement by joining Google as head of its new office in China.
"This lawsuit is a charade," Google and Lee said in court documents filed before a Wednesday hearing in Seattle. "Indeed, Microsoft executives admitted to Lee that their real intent is to scare other Microsoft employees into remaining at the company."
In another filing this week, Lee claims that Microsoft chairman Bill Gates in a July 15 meeting told him, "Kai-Fu, (CEO) Steve (Ballmer) is definitely going to sue you and Google over this. He has been looking for something just like this, someone at a VP level to go to Google. We need to do this to stop Google."
Last week, Google said it had hired Lee to lead a new research and development centre in China and serve as president of its Chinese operations.
In its suit, Microsoft said Lee's move "may also violate, or threatens to violate, Lee's other contractual obligations, such as his promises to maintain in strict confidence Microsoft confidential, proprietary and trade secret information."
Microsoft also asked the court for a temporary restraining order "to prevent the actual and substantial injury that will result if Dr. Lee is allowed to violate his noncompetition promises."
The court is expected to issue a ruling on Microsoft's motion for a temporary restraining order Thursday.
Google and Lee contend that Lee is not doing anything at Google that would compete with what he did at Microsoft.
Google and Lee also asked a California court to declare Microsoft's non-compete provision invalid.
Google appears to be taking advantage of a California rule that frowns on non-compete contract clauses, and a war over courtroom jurisdiction could loom.
