Kasparov - Karpov 1987 in Seville/Spain
Karpov qualified by winning the candidates match and was 36 years old when playing against Kasparov (24 years) again. The match was limited to 24 games and held in Spain.
Anatoly Karpov was leading for one point and Kasparov needed a win in the last game to draw the match and retain the title. He played the Reti opening as White and finally managed to win the endgame and the match was drawn.
The result was a tie 12:12, so Garry Kasparov retained the title for another three years.