June 17 (Reuters) - The U.S. Open will be at full capacity throughout its two-week duration in 2021, the United States Tennis Association (USTA) announced on Thursday, making it the first Grand Slam to be played at 100% capacity amid the COVID-19 pandemic. The tournament was held without spectators in 2020 due to the coronavirus pandemic and will be the first Grand Slam to have full attendance since the Australian Open last year. "We are extremely excited to be able to welcome our incredible fans back to the U.S. Open this year," USTA chief executive Mike Dowse said in a statement. "While we were proud that we were able to hold the event in 2020, we missed having our fans on-site, because we know that they are a large part of what makes the U.S. Open experience unlike any other. "Our sport surged in the toughest of times, and this year’s U.S. Open promises to be an unforgettable celebration of the game, those who play it, and those who revel in it." Organisers of the Cincinnati Masters, the tune-up tournament for the Grand Slam, announced last month that they also plan to operate the August tournament in the city at full capacity. read more The USTA said tickets for the Aug. 30-Sept. 12 Grand Slam are set to go on sale from July 13. This year"s Wimbledon men"s and women"s singles finals will be played with capacity crowds in attendance on Centre Court. read more