Usain Bolt wrote on Twitter that he was out for a walk in the French capital when he ran (presumably not at world record pace) into the happy couple, and offered his congratulations.
Needless to say, they - or perhaps their photographer, or the best man - immediately spotted the chance of getting one of the three most famous athletes on planet earth into the album of their big day.
Bolt posed for pictures, though it must be said that his rather uncharacteristically dour expression is a far cry from his normal flamboyant expressions any time there's a camera within 100ft. Either that or the sun was in his eyes.
The sprinter shared the moment with the world via Twitter, saying, "Only in Paris you walking in the square and the bride and groom leave the proceedings to to do this…"
However, our favourite part of the picture is the man standing on the pavement, camera in hand, facing the other way and missing the chance to take a once-in-a-lifetime snap.