Challenge (Scrabble) - Single Challenge

Single Challenge

In single challenge, if a player places a word and his or her opponent wishes to challenge, the challenger may do so with no penalty. If the word is valid, it remains on the board. If it is invalid, it is removed from the board, the challenged player gets back exactly the same letters as he had, and the turn is noted as a pass with a score of zero points. The challenger receives no penalty (point deduction or loss of a turn) no matter if the challenged play is valid or invalid.

A suggested flaw of this is that a player can challenge any word at any time, even words he knows to be valid; since tournament games are usually timed, this can be used to unfairly gain additional time to think about his or her own next turn.