<P> Rugby goalposts are H - shaped, and consist of two poles, 5.6 metres (6.1 yd) apart, connected by a horizontal crossbar 3 metres (3.3 yd) above the ground . </P> <P> At the beginning of the game, the captains and the referee toss a coin to decide which team will kick off first . Play then starts with a drop kick, with the players chasing the ball into the opposition's territory, and the other side trying to retrieve the ball and advance it . If the ball does not reach the opponent's 10 - metre line the opposing team has two choices: to have the ball kicked off again, or to have a scrum at the centre of the half - way line . If the player with the ball is tackled, frequently a ruck will result . </P> <P> Games are divided into 40 - minute halves, with a break in the middle . The sides exchange ends of the field after the half - time break . Stoppages for injury or to allow the referee to take disciplinary action do not count as part of the playing time, so that the elapsed time is usually longer than 80 minutes . The referee is responsible for keeping time, even when--as in many professional tournaments--he is assisted by an official time - keeper . If time expires while the ball is in play, the game continues until the ball is "dead", and only then will the referee blow the whistle to signal half - time or full - time; but if the referee awards a penalty or free - kick, the game continues . </P> <P> In the knockout stages of rugby competitions, most notably the Rugby World Cup, two extra time periods of 10 minutes periods are played (with an interval of 5 minutes in between) if the game is tied after full - time . If scores are level after 100 minutes then the rules call for 20 minutes of sudden - death extra time to be played . If the sudden - death extra time period results in no scoring a kicking competition is used to determine the winner . However, no match in the history of the Rugby World Cup has ever gone past 100 minutes into a sudden - death extra time period . </P>

What is the duration of a rugby match