Mardy Fish was supposed to be a commentator this week, not a competitor. The former world No. 7 was not originally scheduled to play a tournament between Atlanta and Cincinnati.

But in coming to Washington, D.C. for television duty, he found a doubles partner in Grigor Dimitrov and the two defeated former Wimbledon champions Jack Sock and Vasek Pospisil in the opening round, 6-7 (2), 7-6 (5), [10-8]. Fish and Andy Roddick reached the doubles quarterfinals in Atlanta last week. He came to the Citi Open to do some commentary for the first time.

"I had added this for Tennis Channel," he said, "Thought it would be a good idea if I was here to play some doubles as well."

The partnership with Dimitrov was arranged through text message. The two faced two match points in the second set, but came back to win the tiebreak and the match.

"I felt like the old guy out there for sure. Basically I felt like the worst player most of the time," said Fish, who has not played regularly on tour since 2012 because of a heart problem and subsequent anxiety disorder. But it was fun to be out there competing. Grigor was playing great today. We were looking for that break to get back in it. We stayed with it and got it.

"The other team played fantastic," he added. "It was really fun to go there and compete."

Fish and Dimitrov will next meet Rohan Bopanna and Florin Mergea, who won against another attention-grabbing pair, Andy Murray and Daniel Nestor. Fish is retiring from competitive tennis following the hard-court season.