In years past, a tie in a world championship match was no problem -- the champion kept his title and the challenger had to go back into a three-year qualifying cycle.
However, when the chess world was reunified in 2006 after a 13-year split, there were two world champions and no challenger and a reliable method of breaking a tie needed to be codified.
Chess, like soccer, is a game where many games are drawn, so the need for tie-breaks in tournaments and matches is a frequent occurrence and many methods have been used.
In 1972, Australia's top player Max Fuller tied for second in the south-east Asian zonal championship, a world championship qualifier, but after an inconclusive playoff picked the wrong envelope and missed out on a place in the interzonal and the International Master title -- a title he never subsequently achieved.
Playing an indefinite number of extra games is rarely feasible so, ever since the roulette wheel fiasco
of 1983, games with an accelerated time limit have been preferred to determine a winner.
Now that world champion Viswanathan Anand and challenger Boris Gelfand have fought themselves to a 6-6 standstill after almost three weeks, their fates will be decided in a single day; on Wednesday Anand and Gelfand will play up to 15 games, in sets of two or four, at faster and faster time limits.
"I don't know if it is possible to train for these things, but it is certainly an abrupt shift in the tempo of the match," said Anand when he was asked if there was anything he could do to prepare for the coming day of fast chess. "I will just play my best chess -- that's all I can do."
Should the players remain tied after each set of tie-break games, the 15th and final game will be an Armageddon game, where white is given five minutes, black four, and if the game is a draw, black will be the world champion.
Armageddon is the nightmare scenario; if Gelfand draws with the black pieces in the Armageddon game, he will have become world champion without outscoring the former champion -- an end to a century and a half of tradition.
Rapid tie-breakers have been compared to penalty shoot-outs in soccer, though a better analogy would be deciding a Test series by playing one-day games and then T20 games if those are also equal.
Anand was once the fastest player in the world -- "he moves faster than God thinks", said one pundit after watching a young Anand demolish a Grandmaster
using eight minutes thinking time. In addition, his career record against Gelfand at rapid and lightning chess is 22.5-12.5, so one might expect that Anand would be hot favourite to win the tie-breakers.
However, on his road to the top, the Indian has twice played important tie-breakers, and twice lost.
In 1994, Anand let slip a 3-1 lead in regulation time against America's Gata Kamsky, in the world championship candidates semi-finals on home soil, and lost the tie-breakers.
Even more painfully, in 1998 when Anand was battling for the (lesser) FIDE world title against Anatoly Karpov, he came back from one down with one to play to tie the main match 3-3, only to lose to the older and slower Karpov 0-2 in the tie-breakers.
In recent years, Anand has well and truly shaken off his reputation as a choker
, but he has never needed tie-breakers to win his world title matches and the thought of sitting down in Moscow's Tretyakov Gallery with plenty of prize money at stake on some fast games may bring back unfortunate memories.
Gelfand has never had much of a reputation as a rapid player but he twice won the rapid section of the Amber Exhibition Tournament in Monaco, once ahead of Anand.
More recently Gelfand survived a hair-raising rapid playoff against Kamsky in the candidates semi-finals in 2011; a match so tight that had Kamsky found one good move at the right time
, he would have eliminated Gelfand from world championship contention.
In addition, both players are in their 40s, an age when speed and reflexes are on the wane, so neither can be sure of controlling the tie-breakers, especially when and if the time limit drops to five minutes plus a three-second increment per move for the entire game.
After 10 moves of Monday's final regulation game, both players might have dreamed of the victory that would have avoided the tie-breakers. The game was completely unbalanced, materially and positionally, yet somehow, as so often in this match, every time one player threatened to grab the initiative, his opponent was ready to neutralise that effort and balance the game.
Their reward is a day -- possibly running for 15 games from noon until after 9pm Moscow time -- of thud and blunder chess, after which the world champion will be the player who better controls his nerves game after game, hour after hour. Maybe the roulette wheel was a more humane way
to find a winner after all.
World Championship 2012 Game 12
White: V. Anand
Black: B. Gelfand
1.e4 c5 2.Nf3 Nc6 3.Bb5 e6 4.Bxc6 bxc6 5.d3
Varying from game 10's 5.b3, which was well met by 5...e5!.
5...Ne7 6.b3 d6 7.e5! Ng6 8.h4!
"A brilliant move," said Gelfand, who had been hoping for 8.exd6 Qf6! Instead Anand makes a long-term sacrifice of a pawn to ossify Gelfand's pawn structure.
8...Nxe5 9.Nxe5 dxe5 10.Nd2 c4!
After a 39-minute think, Gelfand decides to return the pawn immediately, and give up a second if need be. "Boris reacted well," said Anand "10...c4 showed that he was very alert."
A more greedy player might have gone for 10...Qd5!? 11.0-0 Qd4 12.Rb1 Qxh4 with two extra pawns but difficult times ahead.
11.Nxc4 Ba6 12.Qf3 Qd5! 13.Qxd5
"Anand's decision to take the pawn is hard to explain," said Anand's old rival Vladimir Kramnik, "a sign that Vishy is out of shape or that tiredness has started to play its role".
Gelfand was not so critical, saying that "after 13.Qg3 Bxc4, I get rid of my bishop -- it is my dream".
13...cxd5 14.Nxe5 f6 15.Nf3 e5 16.0-0 Kf7 17.c4 Be7 18.Be3 Bb7
"After I won the pawn black was always going to have compensation, with his bishop pair and the open files on the queenside," admitted Anand. In fact Anand's main advantage lies not in his extra pawn but in his extra half hour on the clock.
19.cxd5 Bxd5 20.Rfc1 a5 21.Bc5 Rhd8 22.Bxe7 Draw Agreed
Objectively the correct result, but with Gelfand having only 16 minutes left in which to make his last 18 moves, Anand was expected to keep pushing. "To play for a win, you need some pieces left," the world champion explained. "Boris' position was very easy to play, so I didn't see any point in playing on. Here we have only drawn when the game is going nowhere."
Kramnik put a different spin on Anand's draw offer -- "It is a clear sign that Vishy is lacking self-confidence."