NEW YORK, NEW YORK - AUGUST 31: John Isner of the United States waves to the crowd after a final career match loss against Michael Mmoh of the United States during their Men's Singles Second Round match on Day Four of the 2023 US Open at the USTA Billie Jean King National Tennis Center at USTA Billie Jean King National Tennis Center on August 31, 2023 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Al Bello/Getty Images)
CNN  — 

John Isner waved farewell to singles tennis in a way fitting of the 38-year-old’s long career on the court.

In another tennis marathon, the giant was felled by fellow American Michael Mmoh in a five-set thriller, bowing out of his singles career with a 3-6 4-6 7-6 6-4 7-6 defeat in the US Open second round.

“Yeah, it’s tough,” an emotional Isner said on-court following his loss.

The 6’10” American was in control of proceedings after racing to a 2-0 lead after two sets and, as it has throughout his career, Isner’s serve was proving too much for his opponent, but Mmoh found a way to battle back.

Aug 31, 2023; Flushing, NY, USA;  John Isner of the United States hits a shot against Michael Mmoh of the United States on day four of the 2023 U.S. Open tennis tournament at the USTA Billie Jean King National Tennis Center. Mandatory Credit: Jerry Lai-USA TODAY Sports

Mmoh won the third set following a comfortable 7-3 win in the tiebreak and then took the fourth set 6-4.

At two sets apiece, a winner-takes-all fifth set would decide the winner and who would progress to the third round.

In a set full of tension and twists and turns, Isner had the opportunity to continue his singles career but couldn’t convert a match point at 5-4. The match then headed to a tiebreak where Mmoh’s energy proved too much for the towering Isner, taking the tiebreak 10-7.

“This is why I worked as hard as I have my whole life to play in atmospheres like this and of course I may not win them all as we know, just like today,” Isner added holding back the tears.

“But to play in front of this crowd and have the support I had is pretty special so thank you.”

Aug 31, 2023; Flushing, NY, USA;  Michael Mmoh of the United States celebrates winning a point against John Isner of the United States on day four of the 2023 U.S. Open tennis tournament at the USTA Billie Jean King National Tennis Center. Mandatory Credit: Jerry Lai-USA TODAY Sports

An almost four-hour long marathon match seems an appropriate way for Isner to end his singles career. The 16-time winner on the ATP Tour will be most remembered for taking part in the longest singles match of all time.

Squaring off against Frenchman Nicolas Mahut at Wimbledon in 2010, Isner took a 6-4 3-6 6-7 7-6 70-68 win after a staggering 11 hours and five minutes of play, breaking numerous records in the process.

While Isner’s singles career is now over, he will have to pick himself up to feature alongside fellow American Jack Sock in the first round of the men’s doubles.

Mmoh will now face British player Jack Draper in round three of the US Open.