Early career

Mmoh enjoyed early success on the ITF Futures tour, winning three titles before turning 18.

2016–17: ATP, Grand Slam and top 200 debut

In February 2016, Mmoh qualified for his first ATP-level tournament at Memphis by defeating fellow Americans Dennis Novikov and Bjorn Fratangelo. He then lost in the first round to eventual finalist Taylor Fritz, the highest ranked American teenager at the time. Following his fourth Futures title, Mmoh was awarded a wildcard into the Miami Masters, where he lost to Alexander Zverev, the top-ranked 18 year-old in the world, after dropping two tiebreaks.

In September 2016, Mmoh broke into the top 300 for the first time by reaching the final of the ATP Challenger event at Tiburon as a qualifier.

In November 2016, he reached the Top 200 and also won the 2017 Australian Open Wild Card Challenge largely by winning his first career Challenger title at Knoxville. He would claim another Challenger title the following summer in August 2017 at Lexington.

2018: Top 100, First ATP wins & quarterfinals, Masters third round

To start off the 2018 season, Mmoh recorded his first career ATP-level match wins by defeating Federico Delbonis in the first round of the Brisbane International and world No. 33 Mischa Zverev to make the quarterfinals, where he lost to Alex de Minaur.^[5]

At the 2018 Miami Open he reached the third round as a qualifier for the first time at a Masters level defeating 12th seed Roberto Bautista Agut for his first top-15 win and the biggest of his career.^[6]

He entered the main draw at the 2018 Wimbledon Championships for the first time at this Grand Slam as a lucky loser. He reached the top 100 at World No. 97 on 1 October 2018.

2019–20: First Grand Slam win

In January 2019, Mmoh qualified for the first time via ranking in a Grand Slam main draw at the 2019 Australian Open where he lost in the first round to Radu Albot.

At the 2020 Australian Open, Mmoh recorded his first main draw victory with a straight sets win over Pablo Andújar as a wildcard. Following his Australian Open performance, Mmoh qualified for the main draw at the 2020 US Open, where he won his first round match against João Sousa in four sets, and also at the 2020 French Open, where he lost in the first round.

2021–22: ATP quarterfinal, Out of top 250

At the 2021 Australian Open he reached again the second round in a five set stunning comeback against Viktor Troicki but lost to second seed Rafael Nadal in the next round.^[7]

He received a wildcard for the 2021 Miami Open.

In 2022, he entered the 2022 U.S. Men's Clay Court Championships as a lucky loser directly into the second round replacing top seed Casper Ruud who withdrew in the last minute. He won his first match defeating Sam Querrey to reach the quarterfinals^[8] but withdrew due to injury.^[9]

Mmoh won a wildcard entry into the main draw at the 2022 French Open by winning the Roland Garros wildcard challenge.^[10]

2023: Best season: Two Major third rounds, fourth ATP quarterfinal, top 85

Mmoh's first tournament of the year was in Pune, where he defeated local wildcard Manas Dhamne in the first round^[11] before losing to the 6th seed, Filip Krajinović in the second round.^[12]

He then entered the 2023 Australian Open as a lucky loser after the withdrawal of David Goffin and won his first round match, defeating fellow qualifier French Laurent Lokoli, after saving a match point in the third set. He then defeated 12th seed Alexander Zverev in the second round.^[13][14] He became the fifth player to make it as a lucky loser to the third round; the furthest a lucky loser had made it at this Major is the fourth round (Stéphane Robert in 2014).^[15] As a result he moved up 25 positions back into the top 100 to a new career-high singles ranking of No. 83 on 30 January 2023.^[16]

In February, he lost in the first round at the Dallas Open to eventual champion Yibing Wu. The following week, he reached the round of 16 at the Delray Beach Open by defeating wildcard Aleksandar Kovacevic in three sets.^[17] He then reached the quarterfinals after upsetting third seed Denis Shapovalov, also in three sets.^[18] As a result, he reached a new career high ranking of No. 82 on 20 February 2023.

In early March, Mmoh suffered a leg injury at the Mexican Open during his second round match against Tommy Paul and did not return to competition until May at the French Open, where he lost in the first round to ninth seed Taylor Fritz. He entered the 2023 Wimbledon Championships as a lucky loser again and defeated 11th seed Félix Auger-Aliassime in the first round.

In July 2023, in Washington, D.C., he defeated world No. 17 Hubert Hurkacz, and in Winston-Salem he beat Marcos Giron as a wildcard.^[19] Next he defeated 11th seed Karen Khachanov in the first and John Isner in the second round of the US Open.^[20] It was Isner's last singles match before retiring from professional tennis.^[21][22]

Singles: 18 (11–7)

More information Result, W–L ...

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Win	1–0	Oct 2014	USA F29, Brownsville	Futures	Hard	Dennis Novikov	7–6(7–5), 6–1
Win	2–0	Jul 2015	USA F22, Godfrey	Futures	Hard	Jared Hiltzik	6–3, 3–6, 7–5
Win	3–0	Oct 2015	USA F30, Houston	Futures	Hard	Lucas Gómez	6–3, 6–2
Loss	3–1	Jan 2016	USA F2, Long Beach	Futures	Hard	Yannick Hanfmann	4–6, 0–6
Win	4–1	Mar 2016	USA F10, Bakersfield	Futures	Hard	Casper Ruud	6–4, 6–7(5–7), 6–1
Loss	4–2	Oct 2016	Tiburon, USA	Challenger	Hard	Darian King	6–7(5–7), 2–6
Win	5–2	Nov 2016	Knoxville, USA	Challenger	Hard (i)	Peter Polansky	7–5, 2–6, 6–1
Loss	5–3	Jul 2017	USA F23, Wichita	Futures	Hard	Christian Harrison	6–1, 2–6, 5–7
Win	6–3	Aug 2017	Lexington, USA	Challenger	Hard	John Millman	4–6, 7–6(7–3), 6–3
Win	7–3	Sep 2018	Columbus, USA	Challenger	Hard (i)	Jordan Thompson	6–3, 7–6(7–4)
Win	8–3	Sep 2018	Tiburon, USA	Challenger	Hard	Marcel Granollers	6–3, 7–5
Loss	8–4	Sep 2019	Cary, USA	Challenger	Hard	Andreas Seppi	2–6, 7–6(7–4), 3–6
Win	9–4	Nov 2019	Knoxville, USA	Challenger	Hard (i)	Christopher O'Connell	6–4, 6–4
Loss	9–5	Apr 2022	Tallahassee, USA	Challenger	Clay	Wu Tung-lin	3–6, 4–6
Win	10–5	Sep 2022	Cary, USA	Challenger	Hard	Dominik Koepfer	7–5, 6–3
Win	11–5	Oct 2022	Fairfield, USA	Challenger	Hard	Gabriel Diallo	6–3, 6–2
Loss	11–6	Nov 2022	Drummondville, Canada	Challenger	Hard (i)	Vasek Pospisil	6–7(5–7), 6–4, 4–6
Loss	11–7	Nov 2023	Yokkaichi, Japan	Challenger	Hard	Zizou Bergs	2–6, 6–7(2–7)

Close

Doubles: 1 (1–0)

More information Result, W–L ...

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Win	1–0	Sep 2019	Cary, USA	Challenger	Hard	Sekou Bangoura	Treat Huey John-Patrick Smith	4–6, 6–4, [10–8]

Close