"It was the most difficult game in my life, the most intense match I ever played," Anand told a news conference after his win in the conclusive 12th game, that lasted more than four and half hours on Tuesday night.
"We were under enormous pressure in the final stages of the game," added the Indian, who played with the black pieces in the title-decider but needed no invitation to take advantage of some Topalov errors.
The epic battle that started in the imposing building of the Central Military Club in the Sofia downtown on April 24 maintained its suspense until the very end with a tie-breaker in rapid chess looming on the horizon.
Topalov, 35, admitted before the 12-game match he had the advantage of being five years younger than Anand and offered the Indian a test in the last game with score locked at 5.5-5.5.
The crucial encounter turned to a dynamic game with chances for both sides but Anand proved up to the task and displayed one of his typical performances with Queen's gambit on the board.
"Topalov was and still is a great opponent, he's one of the best players in the world," added Anand, proclaimed "Mind King" by the fans in his homeland.
Anand, who comes from southern India, became the first Asian to win the FIDE world chess championship after defeating Spain's Alexei Shirov in Tehran in 2000.
The Indian maestro, who will receive 1.2 mln euros ($1.52 million) in prize money, did enough to put his name in the history book as he's the first player to have won the world championship in three different formats - knockout, tournament and final match.
Analysts said the duel in Sofia was roughly equal with Anand winning thanks to his ability to shine at key moments while local hero Topalov will probably look back in anger to an 11th game where he wasted some very good chances.
