Yusuf Eren Kavri: The National Master Behind Mattheii
Meet Yusuf Eren Kavri, known to the online chess world as Mattheii. A certified National Master, he has spent five years quietly building one of the more respectable blitz chess resumes on the internet, with a peak blitz rating of 2800 (2800 (2026-10-05)) and a bullet peak of 2806 to match. His game of choice is blitz, his hobby is making your Sunday feel shorter, and his opening preparation has gone from winging it to genuinely scary.
The Long Climb
Mattheii's first recorded blitz game arrived in July 2021, a 2147-rated win that now reads like a founding myth. What followed was less a rise than a slow excavation: over 1,100 rated blitz games and nearly 800 bullet games later, he pushed into the 2700s in late 2025 and touched 2800 in October 2026. Along the way he stitched together a 16-game winning streak, survived an 8-game slump without visible drama, and deepened his median prep from a cheeky depth of 1 in 2021 to a studious 5 by 2025.
Opening Repertoire: A d4 Devotee
As White, Kavri is a queen's pawn loyalist with almost ceremonial devotion: in 2026, 188 of his 195 White games began with 1.d4. His pet weapon is the King's Indian Defense: Makogonov Variation, good for 54 blitz games and a 59% win rate, backed up by solid Queen's Gambit Declined structures where his bullet results are excellent.
Here is the pet setup in action:
Against 1.e4 he trusts the Sicilian Defense: Alapin Variation, 41 blitz games at a 53% win rate, while the English Opening: Agincourt Defense has been a sneaky scorer as Black. For special occasions, there is the Australian Defense, a rare beast he keeps in the bullet drawer for the truly brave.
Playing Style: The Long Grind
Hoping for a flashy quick win? Bad news. His victories average nearly 85 moves, roughly 82% of his games reach an endgame, and his first capture usually waits until move seven. He would rather squeeze a position than sac a knight for applause.
- Endgame frequency of 82.5%: the signature of a grinder
- An 82% comeback rate: being worse never means being lost
- Over 1,700 rook checks delivered, his favorite way of saying hello
- 58.5% win rate when he lands the first check of the game
- A tilt factor of just 8, roughly the emotional stability of a library
- 99% of his losses are competitive: he simply does not do blowouts
One statistical quirk: almost nobody actually gets mated by him. The resignation flag does the heavy lifting, and nearly half of his games end in an early wave of the towel, so dead-lost positions in his games rarely linger long enough to become art.
Rivalries and Recurring Guests
Every grinder has a nemesis, and for Mattheii it is tyrionlannister42, his most-played opponent at 18 meetings and holder of a 6-10-2 edge that clearly needs revisiting. Then there is Luis Guillermo Antúnez Soler, whom Kavri is still chasing a first win against at 0-5-1, and the terrifyingly fast Andrew Tang, against whom he has managed 1-6. On the brighter side, he owns a winning 4-3 score against Димитрий Король.
Clocks, Calendars and Quirks
- Best time to play: 5 AM, according to the data, and we have questions
- Morning sessions at 8 AM run at a 65% win rate, his best high-volume hour
- Sundays are his day: a 63% win rate while everyone else is resting
- The 11 PM slot is a trap, where his win rate sags to 40%
- His official Rapid career: played 1, won 1, win rate 100%, retired undefeated
- In 2026 opponents finally started letting him land mates, a career-best output
The Bottom Line
Yusuf Eren Kavri is the kind of National Master who does not need fireworks. He takes your favorite line, walks it into a long technical battle, out-grinds you with a rook that checks more often than most people text, and does it all before most of his opponents have finished their coffee. If you queue against Mattheii on a Sunday morning, bring your own. He has clearly had his since five.