Double Olympic medallist Nick Willis has upped his Gold Coast Commonwealth Games preparations with a sub-four minute mile at his US base in Michigan.
Willis, who won 1500m silver at the 2008 Beijing Games and bronze in Rio two years ago, clocked a winning 3min 57.99sec at the indoor Wolverine Invitational meeting in Ann Arbor.
He beat compatriot and fellow Rio Olympian Hamish Carson, who took second in 3:58.68.
It was the 29th time Willis has ducked under four minutes for the mile, and well outside his all-time best of 3:49.83 for the distance, set in June 2014.
Carson's time was his fourth-quickest for the mile, and the sixth time he has bettered four minutes.
Willis, who won 1500m gold in Melbourne 2006, is gunning for his fourth Commonwealth Games and has his eye on a challenging 1500m-5000m double.