Biggest umpire mistake in history?

Agnieszka Radwanska and Mona Barthel were battling during a tense 3rd set in Doha on a 3-6 6-3 4-2 scoreline for the Pole. Aga won the first point with a great passing shot, and that would have been 0-15 for Radwanska. Instead, the umpire called the point in favor of Mona (15-0). The situation snowballed with Barthel winning 3 of the following 4 points. The score would have been 40-30, but instead the umpire gave the game to the German thinking that she won it at 15.

The funny part

No one realized the mistake during the game, and both Agnieszka and Mona sat down for the change over when the team of the Pole complained. Eventually, the umpire agreed that it was 40-30, the players went back on court, and Radwanska conquered that game. Aga won the match 3-6 6-4 7-5, but that wasn’t great from both the umpire and Barthel that didn’t complain at all when the mistake was uncovered.

That’s part of tennis.