This is the kind of position which seems to be quiet in the exterior, but both sides have to be careful with their manners in the middlegame.
White has a visibly weak pawn structure on the queenside. In exchange, he has a bishop in the endgame, against the opponent's knight.
After all, Black's position doesn't have many weaknesses, and the white bishop is not able to show much influence in the game.
Black commits a grave error, blundering away his queenside pawn.
White pays back the compliments, not noticing Black's tactical error. The tension of the board is palpable here.
Fedoseev has made good progress in the past few moves and enjoys a good edge in the endgame here. All his pieces are active now, especially his own king which has gone on a long sojourn into Black's position.
The white king continues his march, driving deep into enemy territory. In most of the endgames, what makes a difference in piece activity can be the king, and the current game is a good example of that.
Starting the game patiently with a quiet opening setup, Fedoseev conducted a patient game and ultimately created chances in a good endgame.
Being a time with fast time controls, there were mistakes from both players, but Fedoseev impressed with his play in the endgame. What tilted the game in his favor was the white king, which drove deep into the enemy position and became a huge force, helping white to win the game.