One team is "dormie", meaning that they cannot be beaten, if they lead by the number of holes left to play. No matches go to extra holes.
For each series of matches, the two captains submit their line-ups (in order, one to four for the foursomes and fourballs and one to 12 for the singles) independently of each other. Their lists are then put together to decide who plays who.
On Saturday night, the captains each nominate a player to go in "the envelope". Should a player be unfit to play, the envelope of the opposing team is opened and the "match" removed from the draw and deemed a half. If a second player is unfit to play, his match is forfeited to the opposition.
Both players play their own ball, the lower score on each hole counting as the team score.
Each partner takes alternate shots until the hole is completed. One player tees off at the odd holes, the other on the evens.
Match play, featuring 28 different matches: four morning foursomes and four afternoon fourballs tomorrow and Saturday; 12 singles on Sunday.
The first of 37 previous matches took place in 1927 when the British team sailed to the States after a subscription raised by Golf Illustrated magazine. After America won 18 of the first 22 matches, Great Britain and Ireland expanded to include continental Europeans. Europe has won five of the last seven matches.
The US, after their 16 to 11 victory at Valhalla two years ago, hold the Cup. The Americans last won it back-to-back in 1993.
No cumulative scores as in medal play; holes won, lost or halved. Match status described as, say, one-up or two-down; match results recorded as 3&2 (three holes up but only two holes to play), or one hole, etc.
28 available (one per match, half a point each for tied matches). The US need 14 points to retain the Cup, Europe need 14 to regain the Cup.
Presented in 1927 by St Albans seed merchant Samuel Ryder to the Professional Golfers' Association for a competition between the British and American pros. It is 17in tall, weighs 4lb and is made of gold. The golfer depicted on the top is Abe Mitchell, friend and personal instructor to Ryder and who should have been the first British captain but for going down with appendicitis.
... and not forgetting Twitter
So Monty hasn't banned his team from using Twitter during the Ryder Cup after all, as Ian Poulter tweeted triumphantly earlier this week. Corey Pavin, though, has imposed a ban until after the event – but red-blooded Americans won't put up with that, will they?
Here are the players to follow over the next few days:
Europe: Ian Poulter (@ianjamespoulter); Graeme McDowell (@Graeme_McDowell); Rory McIlroy (@McIlroyRory); Francesco Molinari (@F_Molinari).
US: Stewart Cink (@stewartcink); Bubba Watson (@bubbawatson); Rickie Fowler (@RickieFowlerPGA); Zach Johnson (@ZachJohnsonPGA); Hunter Mahan (@HunterMahan); Corey Pavin (@RC_CAPTAIN_2010).