MOSCOW (Reuters) - Former Soviet world chess champion Vasily Smyslov died on Saturday of heart failure, Russian television reported.

Smyslov, who turned 89 on Wednesday, was taken to a Moscow hospital earlier in the week after complaining of heart problems. He died on Saturday morning, NTV reported.

Smyslov was best remembered for his fierce battles against fellow Russian grandmaster Mikhail Botvinnik in the 1950s.

Their first title match ended in a draw in 1954, allowing holder Botvinnik to retain the crown.

Smyslov finally beat Botvinnik in 1957 to become the seventh world champion, before losing in a re-match the following year.

Smyslov was best known as a positional expert and strong exponent of the endgame, but also contributed to opening theory.

His career in the top flight of world chess spanned some four decades. Aged 63, he was beaten by Garry Kasparov in 1984 in the Candidates Final match for the right to challenge Anatoly Karpov for the world title, which Kasparov went on to capture.

Russian media quoted Karpov as saying: “What I remember most about him was his competitive spirit, but also his delicate sense of humor. It was always very tough playing against him, despite him being more than twice my age.”