7/12/2004 - Mikhail Botvinnik the 6th chess world champion took advantage of automatic rematch clauses when he lost the title to Vassily Smyslov in 1957 by a score of 9.5 - 12.5. Botvinnik got a return match in 1958 and regained his title by defeating Smyslov by a score of 12.5 - 10.5. Botvinnik again took advantage of automatic rematch when he lost to Mikhail Tal in 1960 by a score of 8.5 - 12.5. Botvinnik got a return match in 1961 and regained his title by defeating Mikhail Tal by a score of 13 - 8.
Anatoly Karpov the 12th world champion took advantage of
automatic rematch clause when he lost his title to Garry
Kasparov in 1985 by a score of 11 - 13. Karpov got a rematch
in 1986 against Garry Kasparov. Karpov lost the rematch by a score of
11.5 - 12.5. Karpov also took advantage of the rights of an ex challenger of
the world title one match remove from the challenge.