Hanging on the back wall of the stadium court at the Citi Open is a banner showcasing the tournament’s past champions, a list that dates back to 1969 for the men and 2011 for the women. This year’s Citi Open field features several names from that banner, including the last four champs.

Defending champion Gael Monfils is back as the sixth seed in this year’s tournament; 2015 winner Kei Nishikori is the second seed; 2014 champion Milos Raonic the third seed; and 2013 titleholder Juan Martin del Potro is the 13th seed.

“I love to play this tournament because the quality of the tournament is great,” del Potro, ranked 32nd in the world, said. He leads the group with three Citi Open titles (2008, 2009, 2013). “The high level of the players make a very important tournament on tour.”

The Argentine is most known for his 2009 U.S. Open victory when he was 20 years old, defeating Rafael Nadal in the semifinal and Roger Federer in the final. Del Potro was pegged to become a challenger to the “Big Four” of Federer, Nadal, Novak Djokovic and Andy Murray, but injuries derailed those plans.

His play at Wimbledon last year was the first time he competed in a Grand Slam in two and a half years, after enduring multiple operations on his left wrist. A former world No. 4, del Potro, 28, reached the round of 64 at Wimbledon this year.

Del Potro said his wrist still bothers him from time to time, depending on the weather. And he said if injury forced him to stop playing for an extended period again, he’s not sure he could make another comeback.

Del Potro’s last title was in the 2016 ATP Stockholm in October, against American Jack Sock. For the Citi Open, he said he’s not sure why he’s had such great success at the tournament, but said the event is special to him because a lot of Argentinian fans always come out to support.

“I don’t know,” del Porto said. “I like to play here. I feel like home. I always play good in tennis in the United States, so this tournament is special to me.”

Nishikori also is a past winner at the Citi Open, but didn’t play in last year’s tournament. Like del Potro, he will have to pass a deep men’s singles field that is stacked with top 15 players, including himself, No. 7 Dominic Thiem, No. 8 Alexander Zverev, No. 10 Milos Raonic and No. 11 Grigor Dimitrov.

“The field is very strong this year, a lot of top 10 and 15 players playing and it is going to be tough rounds,” Nishikori said. “But will try to focus on what I have to do on the court and play the best tennis each match and like I said, it is going to be tough … I think it’s going to be a great tournament.”

Nishikori is currently ranked No. 9, the highest of the four most recent Citi Open champions back in the nation’s capital. The 27-year-old from Japan has won 11 men’s singles titles, but none this year. His most recent title came at ATP Memphis last year.

Nishikori said he’s a “little bit disappointed” he hasn’t been winning tournaments recently, but is keeping a positive outlook on matches to come, starting with the Citi Open.

“I try to not think too much,” said Nishikori, who made Wimbledon’s round of 32. “But I have won this tournament and have a good memory playing this center court here and think this is a little advantage for me and the former champions and kind of have a little bit of confidence coming through this tournament.”

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