Law 41A: After a bid, double or redouble has been followed by three passes in rotation, the defender on presumed declarer's left makes the opening lead face down.
It's not just a matter of fleetingly placing the card face down before turning it over. There is a reason for it to be placed face down.
Law 41B says, "Before the opening lead is faced, the leader's partner and the presumed declarer each may require a review of the auction, or request explanation of an opponent's call."
So, give partner and the presumed declarer a chance to speak. It doesn't matter whether they say, "No questions," or "Thanks," or "OK." There ought to be some indication that it is OK to face the opening lead. This pause also gives other players a chance to draw attention to the fact, should the wrong player be trying to make the opening lead.
Jan Peach
QBA Director Accreditation
Article Posted: August 19, 2009