The Tri Nations is an international rugby union competition that is contested annually by Australia, New Zealand and South Africa. The competition is organized by SANZAR, a consortium formed by the three countries' rugby governing bodies - the Australian Rugby Union, the New Zealand Rugby Union and the South African Rugby Union. These three teams have dominated international rankings in recent years and some consider the Tri Nations to be the toughest competition in international rugby.
The Tri Nations will become the Four Nations in 2012 with the inclusion of Argentina as the fourth team go ahead. Argentina has been invited to join but there are a number of conditions that they must fulfill.
The series is played on a home-and-away basis. From the first tournament in 1996 until 2005, the three teams played each other twice. Since then, each team has played the others three times, except in the Rugby World Cup year of 2007 when the series reverted to a double round-robin. Since the inception of the series the games played between Australia and New Zealand also go toward determining the winner of the Bledisloe Cup each year. The Freedom Cup is contested between New Zealand and South Africa, and the Mandela Challenge Plate between Australia and South Africa.
The order of fixtures has changed several times in the history of the series. In the past each team played the others twice. After some tweaking of the schedule it was decided to start the series with two fixtures in either South Africa or New Zealand and move the series to the country that did not host the opening rounds. Under this setup Australia's home fixtures were always the middle two in the series.
The recent reworking of the calendar took effect with the 2006 event. This was the result of a new television deal between SANZAR and broadcasters in the United Kingdom and the SANZAR countries. Each team plays the other three times. In 2006 the series opened in New Zealand and the first four rounds alternated between New Zealand and Australia. The fifth round was in Australia. After a one-week break the series returned to New Zealand and then finished with South Africa's three home fixtures. Each team has two home fixtures against one team and only one home fixture against the other.
The competition begins in July. Originally it had started late in July but, with the expansion of the series, the start date has moved to early in the month. It typically ends early in September. The Tri Nations opens after the completion of the Super 14 competition for the year because players from the SANZAR countries are involved in both.
The winner is determined by a points system:
- 4 points for a win
- 2 points for a draw
- 0 points for a loss
"Bonus points" may also be earned in any given match and count toward deciding the series winner. A total of two bonus points can be possibly scored:
- The Attacking bonus point by scoring four or more tries in the match, regardless of the final result.
- The Defending bonus point by losing by seven points (a converted try) or less.
A victorious team can collect either 4 or 5 points, depending on whether or not it scored 4 tries. A losing team may collect from 0 to 2 points. At the end of the series the team with the most points is declared the winner. If teams end level on points the first tiebreaker is point differential, followed by number of tries during the series. However, the Tri Nations has yet to finish in a tie for the top spot.