Conversation so far:
What happened in the 2009 season?
Warner announced his desire to return to the Cardinals for the 2009 season.
Why did he want to return?
Warner was looking for a contract that would pay him about $14 million.
Did he get that amount?
4, Warner re-signed with the Cardinals to a two-year deal worth $23 million total.
How did he perform that season?
Warner broke the NFL's single-game record for completion percentage in the regular season.

Question: What was the record?
Self-contained rewrite: What was the record for completion percentage in the regular season?