US player Mardy Fish plays a backhand during his fourth round men's singles match at Wimbledon this month. (GLYN KIRK/AFP via Getty Images)

The last time Mardy Fish rolled through Washington, he was overhauling his game with a renewed dedication to fitness in the wake of a serious knee injury. Those efforts catapulted him up the rankings and into the top 10 for the first time in his career.

This week, Fish returns to the nation’s capital as the marquee attraction at the newly rebranded Citi Open tennis tournament. But once again, his visit coincides with a critical transition.

Fish, who holds the top seed in the draw, missed the entire clay court season after he had heart arrythmia diagnosed. Following an inspiring run to the round of 16 at Wimbledon last month — his first action since surgery in May — the 30-year-old tour veteran is still trying to work his way back into form, both physically and mentally.

Rather than join the rest of the top-ranked players at the London Olympics, Fish — who won silver in singles at the Athens Games in 2004 — opted to stay home to get a jump on the hard-court season.

“Playing in the States is my most fun time of year — playing in the summer, playing in the heat,” said Fish, currently ranked 13th in the world. “And I didn’t want to miss that. Two full weeks of playing in the most important time and most fun time for me.”

This year the Citi Open runs concurrently with the Olympics, keeping some more notable players out of the draw at the William H.G. FitzGerald Tennis Center. But what the event lacks in star power, it more than makes up for in intriguing story lines.

As the world’s 17th-ranked player, rising Ukrainian star Alexandr Dolgopolov would have made the cut for the London Games. But by not competing for his country in the Davis Cup, he failed to meet the eligibility requirements and was barred from the tournament. Instead, he’ll be looking to polish his hard-court game and pick up valuable points on the march to the U.S. Open.

Like Fish, fellow American Brian Baker knows a thing or two about comebacks. The 27-year-old is back on tour after a five-year absence that included five major surgeries. Baker, whose ranking skyrocketed from 752 one year ago to 79 this month, matched Fish’s Wimbledon run to earn one of four wild-card entries to this week’s tournament.

James Blake won the Legg Mason back in 2002 and will look to recapture some magic after a difficult season to date.

Talented 19-year-old American Sloane Stephens and 28th-ranked Russian Anastasia Pavlyuchenkova highlight the women’s field for the new simultaneous WTA International level event.

But all eyes will be on Fish, the defending U.S. Open Series winner, as he continues to re-acclimate his body and his mind to the grueling tour schedule in the lead-up to next month’s U.S. Open.

The night after losing a quarterfinal match at the Masters 100 event in Miami in March, Fish awoke in a panic. His heart was racing and he had no way of slowing it down. He had a form of heart arrythmia diagnosed and after attempts to treat the ailment with a night heart-rate monitor failed to produce results, Fish underwent cardiac catheter ablation — a procedure that uses radio waves to destroy the tissue causing the irregular beat. He also cut alcohol out of his diet and significantly reduced his caffeine intake to reduce the chances of another flare-up.

Fish returned to the court last month at Wimbledon, won his first three matches and took the opening set from eventual semifinalist Jo-Wilfried Tsonga before falling in a rain-interrupted match.

“Obviously what he went through has been tremendously scary for him,” said former U.S. Davis Cup captain Patrick McEnroe. “He could have easily lost in the first round at Wimbledon, but he was able to battle through a few matches when he wasn’t anywhere near his best. If he can have success in D.C. and do well at the Masters, he can definitely get back to the level he was playing at last year.”

After a series of hip, elbow and sports hernia surgeries that nearly ended his career, Baker can relate.

“Anytime you go through a major surgery, it just makes it that much tougher to come back,” Baker said. “When you’re out for that long, it takes a while to get back in the flow, feel comfortable and learn how to compete again.”

For Fish, that comfort level comes with the sweltering heat and brutal humidity of D.C. in August. After pulling out of last year’s tournament with a late injury, the second-ranked American hopes to use this week as another step on his road back.

“I know that everything is fine with me, but I’m going to put myself in situations where I’m comfortable,” Fish said. “The hardest part for me is mentally trusting everything. The summer is hard enough because you have to deal with the weather and the conditions you have to play in.

“I’m just doing everything I can to get myself in the best shape I can.”