"It's weird, really weird," Adrian said. "I'd been focused on swimming for so long, and then it was about swimming fast and then it was like you're a veteran and then you look at it now and it's like you're one of the leaders of the team. It feels like it was only a few years ago I was nipping on the heels of Jason Lezak."
Actually, it was eight years ago that Adrian captured his first national title.
But things change, and the search for new American leadership is starting all over again.
From Mark Spitz and John Naber in the 1970s to Matt Biondi and Rowdy Gaines in the 1980s, this changing of the guard has become relatively routine and virtually seamless. This time, it will be a more dramatic transition.
Phelps qualified for his first Olympics as a gangly teenager out of Rodgers Forge in 2000. From the point on, he, Lochte or both have represented the United States at every Olympics or long-course world championship team through the Rio de Janeiro Games last summer. Adrian was right there with them, at all those international meets since 2009.
So with Phelps retired and Lochte suspended, Adrian is in line to become the next face of the U.S. men's team.
"He was a leader in Rio and I think he'll be the leader till he's done," 20-year-old Townley Haas said.
It won't be easy, but nobody is more qualified right now than the 28-year-old Bremerton, Wash., native.
He owns five Olympic gold medals, has a smile that shines as brightly as any of them and a charisma that has made him one of the most popular swimmers. He apprenticed under Phelps and Lochte and, yes, even Lezak. A year ago, he was one of three captains on the men's Olympic team. Today, he's the only one heading to Budapest, Hungary.
One of them is 23-year-old Chase Kalisz, a Bel Air native and Fallston graduate who took home Olympic silver in the 400 individual medley last year and will compete in the 200 and 400 IMs at the worlds.
Last week, he earned his fourth 400 IM national title with a winning time of 4 minutes, 6.99 seconds — the fastest time in the world this year.
"This is the fastest I've ever been at this point [in the season], so I'm really happy with that progress," he told teamusa.org.
Kalisz, who won silver in the event at the 2013 worlds and bronze in 2015, will have a chance to add gold next month.
"I think I'm in a position to be able to race for a title," he told teamusa.org. "I tell people all the time that the best thing that happened to me for this four-year period was me getting silver [in Rio]. It motivates me every single day, I think about it every single thing that I do."
Other teammates, such as 32-year-old Matt Grevers, have been around. The four-time Olympic gold medalist rebounded from a crushing 2016 Olympic trials to reclaim his spot on the U.S. team with a win in the 100-meter backstroke.
Others, such as 22-year-old Ryan Murphy, are still carving out their place. The world-record holder in the 100 back and a three-time Olympic gold medalist in Rio, qualified in the 100 and 200 back despite a less-than-stellar performance.
But the man to watch might be 20-year-old Florida native Caeleb Dressel.
He won two golds on relay teams in Rio, both in relays and now embarks on an ambitious schedule at the worlds. He qualified in six events — the 50 and 100 butterfly, the 50 and 100 freestyle and the 400 and 800 free relay.
"It's incredible," Adrian said when asked about Dressel's feat. "But that's a really grueling schedule at worlds."
If Dressel can even come close to duplicating that feat in Budapest, Durden could have the perfect blend.