How the Olympic Games hockey tournament works:

• Twelve teams in the preliminary rounds in two pools of six

• The men's draw is:

Pool A: Australia, Great Britain, Spain, Pakistan, Argentina, South Africa

Pool B: Germany, Netherlands, South Korea, New Zealand, India, Belgium

• The women's draw is:

Pool A: Netherlands, Great Britain, China, South Korea, Japan, Belgium

Pool B: Argentina, Germany, New Zealand, Australia, United States, South Africa

• Each team plays the other in that pool

• The top two teams in each pool proceed to the semi-finals

• The remaining teams play classification matches for places fifth to 12th

• Semi-final winners play for the gold and silver medals, losers play for the bronze

Competition format

• Teams comprise 11 players, with five interchange players and unlimited interchange allowed.

• Goalkeepers may block or deflect the ball from the goal with any part of their bodies

• Games run for 70 minutes, 35 minutes per half

• Goals can only be scored by a field goal (shot from inside shooting circle, a D-shaped area in front of the opponents' goal), a penalty corner, or a penalty stroke

• In finals, classification matches or games that require a winner to advance to the next round, games tied at the end of regulation time go into extra time of seven and a half minute halves

• First team to score in extra time wins - known as the "golden goal" rule

• If scores are locked at the end of extra-time, a result is decided by a penalty stroke competition

• Each team selects five players who take alternating strokes