David Gillick smashed the Irish 400m record with a run of 45.23 seconds at Switzerland's Atletica Geneve meeting.
Gillick is the European indoor 400m champion
In a tight finish, he held off a strong challenge from Andrew Steele, with another Briton, Martyn Rooney, third.
Gillick's time is a big improvement on the Irish national record of 45.58secs posted by Paul McKee five years ago.
Steele pushed Gillick all the way in Geneva and took 0.08secs off his own personal best, while Rooney posted a time of 46.02secs.