Men's 400 metre freestyle at the Games of the XXXII Olympiad
Venue	Tokyo Aquatics Centre
Dates	24 July 2021 (heats) 25 July 2021 (final)
Competitors	36 from 31 nations
Winning time	3:43.36
Medalists
Ahmed Hafnaoui  Tunisia Jack McLoughlin  Australia Kieran Smith  United States
← 2016 2024 →

Swimming at the 2020 Summer Olympics
Qualification
Freestyle
50 m	men		women
100 m	men		women
200 m	men		women
400 m	men		women
800 m	men		women
1500 m	men		women
Backstroke
100 m	men		women
200 m	men		women
Breaststroke
100 m	men		women
200 m	men		women
Butterfly
100 m	men		women
200 m	men		women
Individual medley
200 m	men		women
400 m	men		women
Freestyle relay
4 × 100 m	men		women
4 × 200 m	men		women
Medley relay
4 × 100 m	men	mixed	women
Marathon
10 km	men		women
v t e

The men's 400 metre freestyle event at the 2020 Summer Olympics was held in 2021 at the Tokyo Aquatics Centre.^[1] It was the event's twenty-seventh consecutive appearance, having been held at every edition since 1904.

In one of the most stunning upsets in Olympic swimming history, Tunisia's Ahmed Hafnaoui became the lowest-seeded swimmer to win gold since 2004, when Kirsty Coventry won the 200 backstroke as the 21st seed.^[2] Entered into the meet ranked 16th with a month-old personal best time of 3:46.16, Hafnaoui dropped almost half a second to qualify for the final in 8th place by just 0.14 s. The youngest swimmer in the final field, the 18 year old Tunisian was third at the 100 m mark, before moving up to second by the 150. Though he was 0.31 seconds behind Australia's Jack McLoughlin at the final turn, Hafnaoui used a blistering final lap to overtake him, recording a winning time of 3:43.36 - nearly three seconds faster than his entry time. By winning the title, Hafnaoui became the first African Olympic champion in this event and the second Tunisian swimmer to win gold, emulating the feats of his idol Oussama Mellouli.

Meanwhile McLoughlin, swimming out in lane 2, moved to the lead at the halfway mark before maintaining his position until the final turn. However, he could not fend off the late charge from Hafnaoui, settling for silver in 3:43.52. Swimming alongside Hafnaoui, the U.S.' Kieran Smith unleashed the second fastest closing split in the field to win the nation's first medal in this event since Peter Vanderkaay in 2012. While Austria's Felix Auboeck was third at the final turn, he narrowly missed the podium to place fourth in a tie with Germany Henning Mühlleitner who was the fastest finisher in the field.

The only defending medallist in the field, Italy's 2016 Bronze medallist Gabriele Detti was more than a second off his national record, clocking a 3:44.88 to take fifth. The only swimmer in the field to dip under the 3:43 barrier, Australia's pre-race favourite Elijah Winnington (3:45.20) shot out to an early lead before starting to fade at the halfway mark and eventually come seventh. The U.S.' Jake Mitchell, who qualified for the Olympics via a time trial, added 0.01 s from his preliminary time to place eighth.

Prior to this competition, the existing world and Olympic records were as follows.

World record	Paul Biedermann (GER)	3:40.07	Rome, Italy	26 July 2009	[3]
Olympic record	Sun Yang (CHN)	3:40.14	London, Great Britain	28 July 2012	[4]

No new records were set during the competition.

The Olympic Qualifying Time for the event is 3:46.78. Up to two swimmers per National Olympic Committee (NOC) can automatically qualify by swimming that time at an approved qualification event. The Olympic Selection Time is 3:53.58. Up to one swimmer per NOC meeting that time is eligible for selection, allocated by world ranking until the maximum quota for all swimming events is reached. NOCs without a male swimmer qualified in any event can also use their universality place.^[5]

The competition consists of two rounds: heats and a final. The swimmers with the best 8 times in the heats advance to the final. Swim-offs are used as necessary to break ties for advancement to the next round.^[6]

All times are Japan Standard Time (UTC+9)^[1]

The swimmers with the top 8 times, regardless of heat, advance to the final.^[7]

Rank	Heat	Lane	Swimmer	Nation	Time	Notes
1	4	2	Henning Mühlleitner	Germany	3:43.67	Q
2	4	3	Felix Auböck	Austria	3:43.91	Q, NR
3	4	4	Gabriele Detti	Italy	3:44.67	Q
4	5	4	Elijah Winnington	Australia	3:45.20	Q
4	5	5	Jack McLoughlin	Australia	3:45.20	Q
6	5	2	Kieran Smith	United States	3:45.25	Q
7	5	1	Jake Mitchell	United States	3:45.38	Q
8	4	8	Ahmed Hafnaoui	Tunisia	3:45.68	Q
9	3	5	Antonio Djakovic	Switzerland	3:45.82	NR
10	5	6	Marco De Tullio	Italy	3:45.85
11	4	7	Guilherme Costa	Brazil	3:45.99
12	4	6	Lukas Märtens	Germany	3:46.30
13	4	5	Danas Rapšys	Lithuania	3:46.32
14	3	7	Marwan El-Kamash	Egypt	3:46.94
15	3	1	Kregor Zirk	Estonia	3:47.05	NR
16	2	4	Alfonso Mestre	Venezuela	3:47.14	NR
17	3	4	Aleksandr Yegorov	ROC	3:47.71
18	5	8	Gábor Zombori	Hungary	3:47.99
19	5	7	Ji Xinjie	China	3:48.27
20	4	1	Kieran Bird	Great Britain	3:48.55
21	3	3	Henrik Christiansen	Norway	3:48.88
22	5	3	Martin Malyutin	ROC	3:49.49
23	3	2	Zac Reid	New Zealand	3:49.85
24	2	3	Martin Bau	Slovenia	3:52.56
25	2	2	Joaquín Vargas	Peru	3:52.94
26	3	8	Lee Ho-joon	South Korea	3:53.23
27	1	5	Eduardo Cisternas	Chile	3:54.10	NR
28	3	6	David Aubry	France	3:55.01
29	2	6	Aflah Fadlan Prawira	Indonesia	3:55.08
30	2	7	Wesley Roberts	Cook Islands	3:55.65
31	1	4	Igor Mogne	Mozambique	3:56.56
32	1	3	Irakli Revishvili	Georgia	3:57.49
33	2	5	Welson Sim	Malaysia	3:58.25
34	2	8	Alex Sobers	Barbados	3:59.14
35	2	1	James Freeman	Botswana	4:03.10
36	1	6	Filip Derkoski	North Macedonia	4:03.34

^[8]

Rank	Lane	Swimmer	Nation	Time	Notes
	8	Ahmed Hafnaoui	Tunisia	3:43.36
	2	Jack McLoughlin	Australia	3:43.52
	7	Kieran Smith	United States	3:43.94
4	4	Henning Mühlleitner	Germany	3:44.07
	5	Felix Auböck	Austria	3:44.07
6	3	Gabriele Detti	Italy	3:44.88
7	6	Elijah Winnington	Australia	3:45.20
8	1	Jake Mitchell	United States	3:45.39