INTERNATIONAL: World number three Alexander Zverev has been thrown out of the Mexican Open after "unsportsmanlike conduct" that saw him attack the umpire's chair at the end of a doubles match in Acapulco.

Germany's Zverev argued with the umpire during the decisive tie-break as he and Marcelo Melo lost 6-2 4-6 10-6 to Lloyd Glasspool and Harri Heliovaara.

Zverev struck the umpire's chair several times with his racquet.

The 24-year-old was the defending champion in the singles event.

"Due to unsportsmanlike conduct at the conclusion of his doubles match on Tuesday night, Alexander Zverev has been withdrawn from the tournament in Acapulco," an ATP statement read.

His opponent Peter Gojowczyk has been given a walkover into the third round.

Zverev believed a ball was incorrectly called out during the tie-break and began yelling at the umpire, with the crowd taking the official's side.

Britain's Glasspool and Finland's Heliovaara then wrapped up the match with an ace on the next point.

Zverev hit the chair with his racquet three times and came close to hitting the umpire's foot at one point.

He continued yelling at the umpire and took another swing as the umpire moved to climb down from his chair.

The ATP defines unsportsmanlike conduct as "any misconduct by a player that is clearly abusive or detrimental to the success of a tournament, ATP and/or the sport".

Zverev is being investigated by the ATP over allegations that he was violent towards a former girlfriend. He has repeatedly denied the claims.