Michael Mackenzie Lowe McDonald (born April 16, 1995) is an American professional tennis player.

[4] While still a junior, he won the men's singles title at the amateur Ojai Tennis Tournament in 2013,[5] and also qualified for the 2013 Cincinnati Masters at age 18 by defeating top 100 players Nicolas Mahut and Steve Johnson.

At the 2015 NCAA Division I Men's Tennis Championship, he defeated top-ranked Axel Alvarez of Oklahoma during team competition.

1 ranked Mikael Torpegaard of Ohio State University for the singles championship at the Michael D. Case Tennis Center, in Tulsa, Oklahoma.

They defeated the team of Arthur Rinderknech and Jackson Withrow from Texas A&M to win the doubles individual championship.

In doing so, McDonald became the first college player to win both the national singles and doubles titles since Matías Boeker of the University of Georgia in 2001.

After the NCAA tournament, on June 16, 2016, he announced that he would not return to UCLA for his senior year, but turn professional.

[6] At age 18, McDonald qualified for the 2013 Western & Southern Open[3] by defeating two top 100 players despite never previously having earned an ATP point.

McDonald was awarded a wildcard into the main draw of the US Open, where he lost to Czech qualifier Jan Šátral in five sets in the first round.

[8] Beginning in late September and lasting through early October, McDonald had an impressive string of results in Challenger-level tournaments, winning his first ITF Pro Circuit title at USA F29 Irvine Futures, as well as reaching back-to-back semifinals in Tiburon and Stockton with impressive wins over three top-150 players.

[12] At Wimbledon, he reached his first Grand Slam third-round by winning his first-ever 5-set match over Nicolás Jarry in the round of 64.

[13] He then proceeded to defeat Guido Pella in straight sets to reach the second week of a grand slam for the first time in his career.

He also participated in the 2019 Delray Beach Open in February, where he achieved his first top 10 win by defeating Juan Martín del Potro in the quarterfinals to reach his first ATP level semifinal,[17] where he lost to Radu Albot.

[18] His good form carried on into the ATP 500 Acapulco tournament, where he reached the quarterfinals, eventually losing to Cameron Norrie in two sets.

At the 2019 French Open, McDonald suffered a serious hamstring injury in his first round doubles match, forcing him to miss the rest of the 2019 season.

Using a protected ranking to enter the main draw at the Australian Open, he was defeated in the first round by 30th seed and world No.

[27] He reached the 4th round of a Major for the second time where he was defeated by fourth seed and eventual finalist, Daniil Medvedev.

Seeded eighth at the Heilbronner Neckarcup, he reached the semifinals where he lost to Daniel Elahi Galán.

[37] Seeded fifth at the Nottingham Open, McDonald's first grass-court tournament of the season, he lost in the first round to Evgeny Donskoy.

At the Nottingham Trophy, he reached the semifinals where he was defeated by qualifier Alex Bolt, who would end up winning the tournament.

Seeded eighth at the Los Cabos Open, McDonald was eliminated in the first round by qualifier and compatriot, Ernesto Escobedo.

[41] He defeated compatriot, Denis Kudla, in the quarterfinals to reach his second Tour-level semifinal and first at the ATP 500 level.

[62] At the Indian Wells Masters, he was ousted from the tournament in the second round by 19th seed and rising star, Carlos Alcaraz.

[78] At the 2022 Rakuten Japan Open Tennis Championships, he won his maiden doubles title partnering Marcelo Melo after defeating third seeds Rafael Matos and David Vega Hernández.

[80] In doubles, he and his partner, Marcelo Melo, upset top seeds Wesley Koolhof and Neal Skupski in the second round.

[95] In doubles, he and his partner, compatriot Ben Shelton, upset fourth seeds Juan Sebastián Cabal and Robert Farah in the first round.

[106] In doubles, he and Frances Tiafoe reached the quarterfinals where they lost to eventual champions Hugo Nys and Jan Zieliński.

[108] In doubles, he and Marcos Giron beat two-time champions Pierre-Hugues Herbert and Nicolas Mahut in the first round.

[116] At the 2023 National Bank Open he reached his first Masters 1000 quarterfinal upsetting sixth seed Andrey Rublev[117][118] and wildcard Milos Raonic before losing to Alejandro Davidovich Fokina.

He received a wildcard for the next Asian swing tournament, the 2023 China Open in Beijing where he lost to Grigor Dimitrov.