[MrZeropage]

This could happen if the last try in the match did not get finished correctly, for example if the player starts the game and then closes the browser.
You being Administrator should see "make winner advance"-links in the tournament-view, just click on this in a match and it will manually do the advancing which normally takes place after saving the score in the match.

Another case this could happen: both players are in a tie and have the same score, then both of them get one more try (again and again...) until there is a real winner.