Willis won at the Ferry Field track in Ann Arbor with a time of one minute 47.01 seconds, less than 1.5sec outside his personal best set four years ago.

He headed off Reebok team-mates Nate Brannen and Andrew Ellerton in a closely-fought contest.

Willis will next race against world 1500m and 5000m champion Bernard Lagat over 1500m at the adidas track classic in Carson California on Sunday. The Wellingtonian won the race last year.

Meanwhile, Olympic Games team-mate Beatrice Faumuina was fifth in the discus at a grand prix meeting in Osaka, Japan.