In 1954, he drew with Vasily Smyslov over 24 games at Moscow, +7 =10 -7, again retaining the title. In 1957, he lost to Smyslov by 9½–12½ in Moscow, but the rules then in force allowed him a rematch without having to go through the Candidates' Tournament, and in 1958 he won the rematch in Moscow; Smyslov said his health was poor during the return match. In 1960, Botvinnik was convincingly beaten 8½-12½ at Moscow by Tal, now 23 years old, but again exercised his right to a rematch in 1961, and won by 13–8 in Moscow. Botvinnik's play was better than in the 1960 match, mainly due to thorough preparation. Botvinnik changed his style in the rematch, avoiding the tactical complications in which Tal excelled and aiming for closed positions and endgames, where Tal's technique was not so outstanding. Also, Tal's health was variable. Finally, in 1963, he lost the title to Tigran Petrosian, by 9½-12½ in Moscow. FIDE had by then changed the rules, and he was not allowed a rematch. The rematch rule had been nicknamed the "Botvinnik rule", because he twice benefited from it.