Umpires are also sometimes less than happy to see him as he has a
reputation for complaining frequently about line calls, an attitude
probably linked to his extremely competitive nature
that was so
evident during one of his matches in Hamburg!! (i think it was the Ljubicic match). he questioned the line call and immediately the umpire said, "Don't start with me Guillermo! I'm not going to play that game with you."
the commentator for our broadcast started laughing and said - "ooh...someone got up on the wrong side of the umpire's chair this morning!"
that whole scene (plus the shocked looked on Guille's face!) just cracked me up!!!