The incident occurred on the M5 motorway as the Aviva Premiership side were heading for the game in south Wales.
The club said via their twitter account: "The Warriors team bus caught fire on the M5 this morning. Discussions are taking place to determine whether the match will go ahead.
"All players and staff are safe and well. We will let fans know as soon as a decision regarding the match has been made."
Saturday's contest was the club's final warm-up before their Aviva Premiership campaign starts with a match at Leicester on September 8.