It may seem strange, but a match officially starts when the captains toss for choice of innings. The umpire at the bowler's end calls Play as a signal that the real business of bowling, batting and fielding is about to start. As soon as the bowler starts his run-up, the ball becomes 'live' - not a term you will find in the Law book - and play has taken place. The call of Play is repeated after any intervals or interruptions to play during the match.