Michael Phelps is participating in his fourth Summer Olympics, a U.S. record among male swimmers. He’s already won 23 medals, including a record-setting 19 golds — including a gold with the 4×100-meter freestyle relay team Sunday night — and could add three more in Rio when he competes in the 100-meter butterfly, the 200-meter butterfly and the 200-meter individual medley.

And winning an individual Olympic medal in a swimming event at the age of 31 might be even more impressive than racking up that record-setting medal count.

Phelps turned 31 in June, which makes him super old in terms of competitive swimming. Over the past 10 Summer Games, the oldest athlete to swim in the finals for the same events in which Phelps is scheduled to compete has been 29 years old, with the average age just under 22 years old. And, not surprisingly, times get slower as an athlete ages.

However, Phelps is no ordinary athlete. His best time of 50.6 seconds in the 100-meter butterfly from the 2008 Summer Games in Beijing as a 23-year-old is only four-tenths of a second better than his best time at the 2016 U.S. trials as a 31-year old (51 seconds). Dating back to 1976, the best time by any Olympic swimmer in the 100-meter butterfly over the age of 30 was Adam Pine in 2008 (52.1 seconds at 32 years old), 1.4 seconds faster than the average speed for that age group. In fact, Phelps’s U.S. trials time is 2.8 seconds faster than the average time for Olympian swimmers in the 24-to-28 year-old age bracket.

His biggest competition in the 100- and 200-meter butterfly events is expected to come from South Africa’s Chad Le Clos and Hungary’s Laszlo Cseh Jr.

Le Clos, who turned 24 years old in April, tied for silver in 2012 in this event, losing to Phelps by 0.13 seconds. Le Clos clocked a time of 51.82 at the 2016 South African nationals, but his best time in this event since the Summer Games in London is 50.56 seconds in 2015.

Cseh doesn’t have the same renown as Phelps, but he is nearly as impressive — particularly given what he’s done in the latter stages of his career. A medalist at every Olympics since he first represented Hungary at the 2004 Olympic Games in Athens, Cseh turned 30 in December and set a meet record for the fastest 100-meter butterfly time at the European championships (50.86). To have one swimmer in his 30s contend for a medal is unheard of. The fact that two could be on the podium illustrates that this could be one of the rarest events in Olympic history.

According to Lauren Neidigh of swimswam.com, Phelps and Le Clos, a swimmer seven years his junior, are projected to post the two best times of the event at 50.3 and 50.4 seconds, respectively. Cseh is expected to battle for bronze with a predicted time of 50.7 seconds.

Cseh and Le Clos also join Phelps as the only swimmers to post a 200-meter butterfly time under 1 minute 54 seconds since the 2012 Olympics. Phelps’s time in the same event was slightly slower leading up to Rio (1:54.84) but still impressive considering his his gold medal-winning time as a 19-year-old during the 2004 Summer Games in Athens (1:54.04). Cseh is the 2015 world champion for this event (1:53.48), and Le Clos won the gold in 2012 (1:52.96).

Neidigh estimates that Le Clos, Phelps and Cseh will be the only swimmers in Rio to post times under 1:53 seconds in the 200-meter butterfly.

2300phelps-age0806-individualPhelps’s 200-meter IM time at the U.S. trials was 1 minute 55.91 seconds, slower than his gold medal-winning times in Beijing (1:54.27) and London (1:54.23) but faster than Athens (1:57.14). Teammate Ryan Lochte, the 2015 world champion, holds the world record (1:54 in 2011), while Kosuke Hagino, the 21-year-old from Japan who figures to be on the podium, has yet to break the 1:55 threshold in this event. His best time in London was 1:57.35 and 1:55.07 since.

Maybe Phelps doesn’t add more gold medals to his already impressive Olympic legacy, but the fact he is in the top three for each of his three individual events at the age of 31 is a remarkable accomplishment. If he does manage to get more hardware around his neck, he might just put his record medal count out of reach for good.

Michael Phelps is focused on making history at his fifth Olympic games in Rio. (Jayne Orenstein/The Washington Post)

Correction: A previous version credited James Sutherland with projected swim times. This has been corrected to Lauren Neidigh.