Nick Willis won his first international medal, a silver at the 2008 Olympic Games in Beijing, when he was 25 years old. This week, the New Zealand harrier will look to repeat that medal feat at the age of 32.

Willis arrives at the 2016 IAAF Indoor Championships in Portland as one of the favorites to contend for the men’s 1500-meter crown. Willis’s personal best of 3:29.66, run outdoors at the Monaco Diamond League meeting last summer, is a New Zealand national record and one of the fastest PBs in the eld. And only four weeks ago, Willis ran the world’s second-fastest indoor mile time of the year — 3:51.06 — to nish a close second at the prestigious Millrose Games in New York City.

The 1500-meter final on Sunday could feature a rematch of that race, as 26-year-old Matthew Centrowitz, who edged Willis by less than a half- second at Millrose, is a likely qualifier. The Kiwi and the American have forged an entertaining rivalry in recent years, trading off triumphs on the international stage. In 2013, Centrowitz took the upper hand by winning the 1500-meter silver medal at the IAAF Championships in Moscow, but the veteran Willis regained his edge a year later at the Monaco Diamond League meeting, where he beat Centrowitz by 0.18 seconds.

Willis again prevailed in a head-to-head race at the 2015 IAAF Championships in Beijing, nishing sixth, two places ahead of Centrowitz. Other exciting duels at the Millrose Games and the 5th Avenue Mile in New York City have only added to the duo’s friendly competition — one that Willis embraces. “I used to love racing @craig_mottram,” he tweeted in February, “and now a great rivalry with @MattCentrowitz is developing.”

Before turning pro in 2005, Willis competed collegiately at the University of Michigan under the mentorship of renowned middle-distance coach Ron Warhurst — a partnership that produced two NCAA titles and helped send Willis to his first Olympic Games in 2004. Willis, who is still coached by Warhurst, now splits time between Ann Arbor, Michigan, and his hometown of Lower Hutt, New Zealand, where as a teenager he set the national high-school mile record by running 4:01.33.

Away from the track, Willis is a father and husband, as well as an avid traveler. In 2015, Willis told Runner’s World that his competitions abroad often double as family vacations with his wife, Sierra, and son, Lachlan. “We basically get to be tourists on someone else’s dime,” Willis told Runner’s World. “It can become a bit routine, so you need to enjoy the culture if you’re doing it as long as I have.”

The 2016 IAAF Indoor Championships will give Willis an opportunity to improve upon his finishes in 2008 and 2014 — both of which saw him disqualified for stepping inside the track. This weekend, the athletes expected to challenge Willis in the 1500 meters include Centrowitz and Morocco’s Abdelaati Iguidir, whose time of 3:34.94, run in Glasgow, Scotland, in February, is the fastest in the world this year.