The Grandmaster Behind blefer66
Zdenko Kozul, known online as blefer66, is a FIDE Grandmaster with a simple life philosophy: play 1.d4, reach the endgame, and outlast everyone. He prefers rapid chess, but his blitz record tells a different story, with more than 37,000 blitz games played since 2019. That is not a typo. The man simply does not stop.
His opening identity is built on the King's Indian Defense and the Sicilian Defense. As White, he has pushed the d-pawn thousands of times, and as Black he happily walks into the sharpest kingside battles. A typical Zdenko game starts like this:
The Marathon Man
Zdenko does not sprint. His average decisive game lasts more than 78 moves, and he reaches an endgame in about 87% of his games. He wins 44% of his White games and 40% of his Black games, which sounds modest until you realize he is playing against the same pool of tough online grinders every single day.
His comeback rate of 87.59% is the stuff of nightmares for his opponents. Even after losing a piece, he still wins about 40% of the time. He also has a knack for landing the first check, and when he does, his win rate climbs to almost 48%. His rook delivers the majority of those checks, which fits a player who loves open files and slow suffocation.
Friends, Foes, and Frequent Flyers
Zdenko has developed some serious rivalries. He has faced honestgirl 239 times, and the score is not in his favor, but he keeps showing up, which is its own kind of courage. The same goes for Safal Bora, whose username has not matched the results. Against szabadaba and Dmitry Tatarinov, however, Zdenko holds the bragging rights.
His longest winning streak was 28 games, and his longest losing streak was 14. Both streaks prove he is willing to ride the rollercoaster all the way down and all the way back up.
Peak Form and Night Owl Habits
Zdenko reached a peak blitz rating of 2959 (2026-04-25) and a rapid peak of 2500 (2026-08-20). His rating graph is a beautiful mess of spikes and dips, which is exactly what 37,000 competitive games look like.
His opening results show where his bread is buttered:
One final quirk: his best time of day to play is 03:00. Zdenko Kozul is a Grandmaster who does his finest work while the rest of the chess world is dreaming of passed pawns.