Meet Sergey Kharitonov (dzuffin)
Sergey Kharitonov, better known on the board as dzuffin, is a FIDE Candidate Master with a serious addiction to bullet chess. With over 18,000 rated games tracked online (and that's just the tip of the iceberg), Sergey has transformed from a casual 1100-rated player in 2019 into a 2500+ blitz behemoth and a 2387 bullet peak. He's the kind of player who treats every queue as an opportunity, occasionally playing 1,500 games in a single month. If there's a clock ticking, Sergey is probably already moving.
His journey reads like a classic chess grind: slow starts, a blitz breakthrough in 2020, a brief retirement in 2023, and then a return with a vengeance in 2025–2026. By February 2026, he hit his all-time high of 2526 in blitz and has maintained a rapid rating above 2200. He's not just a volume player; he's a dangerous one.
Style & Tactics
Sergey is an aggressive, fighting player. He almost never draws (draw rates hover around 3-5% in bullet), and he loves to check. His stats show he delivers checks more often than his opponents, and he converts wins when he's first to give check at a 53.7% clip. He's also incredibly resilient: his comeback rate is 83.55%, meaning he regularly snatches victory from losing positions. His longest winning streak is 10, but his longest losing streak is 13 – clearly a gambler's mindset.
He prefers open positions with the initiative. As White, he opens with 1.e4 in the vast majority of games, and as Black he frequently meets 1.e4 with the Sicilian Defense – especially the Najdorf, Alapin, and Closed variations. The Caro-Kann Defense also appears heavily in his repertoire, both as a defender and an attacker. He's equally comfortable in the Scandinavian and a few offbeat lines like the Amazon Attack.
He thrives in chaos, but his endgame technique is solid – he averages 72.79% endgame frequency, meaning he doesn't just flag people; he outplays them in the final phase. Watch his to see where he's most lethal.
Opening Repertoire
Sergey's opening choices are surprisingly varied for a bullet specialist. He plays the Sicilian Defense with both colors, and his statistics show he scores best with the Najdorf (57.6% in rapid as Black) and the Closed Sicilian (57.1% in rapid). His White repertoire is dominated by the Caro-Kann Defense and the Alapin Variation, where he's above 50% in bullet. He also enjoys the Czech Defense and the Four Knights Game, often venturing into the Bird Opening's Batavo Gambit.
One interesting quirk: he plays the London System Poisoned Pawn line as Black against 1.d4 with 218 bullet games, scoring 43.6%. He's clearly willing to explore unusual theory even in the fastest time controls.
Rivalries & Foes
No grind is complete without rivals. Sergey has battled a handful of opponents dozens of times. His most common nemesis is theawesome_anay, with 71 meetings, where they're nearly dead even (34 wins each with 3 draws). Then comes Peter Large (59 games, slightly behind) and madrook2021 (53 games, where Sergey holds a winning margin). He also has a tough rivalry with lynexeo, who has beaten him 30 times out of 41. These are the names that make his session longer than planned.
Milestones & Numbers
- Peak ratings: 2387 (2026-09-07) (bullet), 2526 (2026-02-25) (blitz), 2430 (2026-04-04) (rapid)
- Career wins: over 8,000 across all time controls
- Most active in 2026: played 1,546 bullet games in July and 1,200 in June
- Has a winning record against players rated above him (68.3% win rate when facing higher-rated opposition)
His rating trajectory is a story of persistence. See for the rollercoaster, or for the overnight explosion.
Personality
Sergey plays at all hours, but his best time is 2:00 AM (when he wins 51.7% of the time). He tilts occasionally – his "tilt factor" is 13, meaning he sometimes lets losses stack up, but his comeback rate proves he never stays down for long. He resigns early only 0.97% of games, so you have to checkmate him to beat him.
Above all, Sergey is a modern chess warrior: thousands of games, endless blitz sessions, and a hunger for improvement. He might not have a grandmaster title yet, but with his work rate, it wouldn't surprise anyone to see him chase the next norm soon.