As black, Petrosian played the Najdorf Sicilian and the French. As white, he often played the English. He had a penchant for moving the same piece multiple times in a few moves, confusing his opponents in the opening and threatening draws by threefold repetition in the endgame. Contrary to Nimzovich, he also had a preference for Knights instead of Bishops.
Spassky, described his style as that of a hedgehog. Just when you think you had caught him, he put out his quills.
By the way, I always thought hedgehogs and porcupines were the same, but they are two distinct species. Both animals have prickly spines, but they are not closely related to each other and differ widely in a number of respects.
Hedgehogs are much smaller than porcupines, about half their size. Another main difference is where and how they live. Hedgehogs can be found across Europe, Asia and Africa. They are solitary animals, hibernate in winter. Porcupines reside in North and South America, as well as Africa, Europe and Asia and inhabit a larger variety of landscapes.
|Porcupine and hedgehog|
Both have spines, but they are very different. The hedgehog is covered by short, thick spines which are permanently attached to its skin. These spines usually lie flat and are harmless - so much so that it is possible to pet a hedgehog. When threatened, hedgehogs will roll into a tight ball so their spines protrude and their hands, feet and faces are tucked away.
|A dog that encountered a porcupine|
Spassky was considered an all-round player with a "universal style." He was also known as a fighter and he often had great ups and downs, so how he would fare going into this match was anyone's guess.
In 1969 Petrosian was defending his title in a rematch against Spassky. When Spassky played Petrosian in 1966 Spassky described the match as part of his learning process. He was thinking of Botvinnik when he had lost his championship to Smyslov and Tahl and had won the rematches. As a result of Spassky's dedication to defeating Petrosian the second time and becoming world champion his motivation seem reduced because in 1972 against Fischer, he did not seem to possess the same drive. Of course, Fischer's phenomenal talent also had something to do with it!
As for this match, the way it started out, it looked like Spassky was not up to the challenge. Petrosian won the first game, then followed two draws, but Spassky scored in games 4 and 5, games 6 and 7 were drawn and then Spassky won game 8 to establish what looked to be an almost insurmountable lead of two games.
Game 9 was drawn and then a small miracle happened: Petrosian won the next two games and, suddenly, after 11 games, the match was tied. Things settled down to what was a more routine thing for a match of this caliber when games 12 through 16 were drawn.
But then Spassky rallied again, winning game 17 which he described as the turning point in the match. In a superior position, Petrosian offered a draw, but Spassky, though strongly tempted to accept, decided that he detected some insecurity on Petrosian's part and declined, believing it was necessary to create the maximum amount of difficulty for Petrosian.
Petrosian drew game 18, but only with some difficulty. Then Spassky won game 19 to regain his two point lead. There were only five games left, so it looked like Petrosian was done, but he scored in game 20 to pull within one point.
Spassky won game 21 to regain his two point lead and that left him needing only one point in the next three games while Petrosian had to do the impossible and score 2.5 out of 3.
Game 22 was drawn and now Spassky needed only a half point. Game 23 started on June 16th and adjourned to be resumed the next day which was Petrosian's 40th birthday. Spassky was up a pawn and had winning chances so Petrosian offered a draw and Spassky was the new World Champion at the age of 32. He had defeated the hardest player in the world to defeat in a seesaw battle that was closer and more exciting than expected by a score of 12.5-10.5.
Here is the very instructive game 19, only 24 moves, where Petrosian was badly outplayed.