It's a ritual everyone who makes the 2012 Olympic team gets to perform, a way to acknowledge they have answered the call to the London Summer Games.
Actually, it seemed more like a wrong number, because until Monday morning, the Loyola Academy grad from Winnetka hadn't swum the 400 competitively in two years.
He made up for both that lost time and time lost early in the race by closing with a rush to earn the second spot in the event.
One of his training partners in Gainesville, Fla., 2008 Olympic relay gold medalist Peter Vanderkaay, won in 3 minutes, 47.67 seconds. Dwyer's time was 3:47.83.
And his best race is the 200, which begins Tuesday. Now he can swim it without pressure, already having achieved his lifelong goal of getting to the Olympics.
"I'm looking forward to that one," Dwyer said.
Dwyer's personal best for 400 before Monday was 3:51.40 from August 2010.
"I knew I could make a big jump," Dwyer said. "I was training with Peter all year, and he was well ahead of all the Americans last year. I knew if I put in the work, it would be a lot better."
Dwyer, an NCAA champion in the 200- and 500-yard freestyles for the University of Florida in 2010, was more than one second out of second place at the halfway mark. In the final 50, both he and Vanderkaay passed race leader Charlie Houchin, who took fourth.
"Coach (Gregg) Troy said everyone would be (close) at the 300, just dig your head down that last 50 and don't breathe," Dwyer said.
Ryan Lochte, who took a step toward replacing Michael Phelps as the sport's reigning superstar when he beat Phelps in the 400 individual medley, saw Dwyer, 23, develop the ability to do that in practice.
"One of the good things about Conor Dwyer is he's not afraid to race me and Peter, people who have been in the Olympics and had gold medals,'' Lochte said. "I think that is what really helped him out that last 200. He has been in our faces every day in practice, and it showed."
Meanwhile, when Christine Magnuson of Tinley Park emerged from the water after getting fourth in her Monday semifinal of the 100 butterfly, the event in which she won a surprise 2008 Olympic silver medal, she was talking of the freestyle.
"Hopefully I can get another swim. If not, I will turn my focus to the freestyle,'' Magnuson said. "But if you get a lane, you get a chance."
She got the last lane for Tuesday's final by posting the eighth fastest time of the two semis, 58.72. That was well behind Dana Vollmer's leading 56.42.
NCAA champion Kevin Cordes of Naperville was the sixth fastest qualifier for Tuesday's 100 breaststroke final.