TMZ broke the story ... Pam filed for divorce in L.A. last week, citing irreconcilable difference. But this week Rick filed his own legal docs -- obtained by TMZ -- in Las Vegas, claiming the marriage should be nullified because Pam deceived him.
Sources connected with Rick will not disclose the nature of the fraud, however they say Rick has solid proof she bamboozled him into marrying her.
The couple married in January 2014.
Rick is also asking the judge to rule there is no community property in the marriage. Rick is loaded ... winning huge sums in poker last year. We're told his fortune is vast ... hers is not.
The annulment was filed by Rick's lawyer, Richard Schonfeld, who also represented Britney Spears in her Las Vegas annulment.
Rick obviously is also asking the judge to deny her spousal support.