Player challenges using instant replay technology made its grand slam debut at the US Open, with the first such test proving the line judge was right on the mark.
American Mardy Fish made the first challenge in grand slam history when at 2:15 pm EST he formally questioned a call during his match against Germany's Simon Greul.
With Fish leading 6-4 6-4 1-0 and Gruel holding advantage on his own serve, the German hit a shot close to the sideline that the line judge called in.
Fish used one of his challenges to question the call. Players, officials and fans at Louis Armstrong Stadium looked at the video review together and the judge's decision was upheld.
The new technology was launched in March for all US Open Series events in North America this summer and has been seen as successful enough to use at the US Open.
Players get two challenges per set and an additional one in a tiebreak.
Despite losing the challenge, Fish won the match 6-4 6-4 1-6 6-3.