One weakness on c6 may not be enough to win, and so White intends to open a second front – by playing b2-b3, he gets the open a-file to enter with his rooks. If this plan had not been available, White would have advanced his kingside pawns to seize space, and combine threats on that flank with pressure on c6.

White has more space, and therefore he refrains from exchanges that do not bring him any concrete benefits.

Black’s main problem is his restricted light-squared bishop. If he is given time, White will play Rf1-f3, and after the queen moves away, the move g2-g4 follows, further restricting Black’s bishop and preparing f4-f5. One can also not rule out the break f4-f5 without the preparatory g2-g4, aiming for an attack on the f-file. Therefore, Black decided on the radical...

It was important to realise that after the opening of the g-file, Black has the resource ...Re8-e6-g6, liquidating the threat of an attack. At the same time, the weakness of the f5-pawn is balanced by that of e3.

Black has no problems at all. The minor pieces with which White might have been able to exploit the f5-pawn have all been exchanged, and Black has substantial pressure on the e- and g-files. Only White has to worry about maintaining the balance, which in the game he was unable to do:

White resigned.

The position is symmetrical, and so is it equal? No! White has the possibility of spoiling his opponent’s pawn structure.

If this were a middlegame, this exchange would have to be very carefully considered, because of the weakening of the light squares around the white king. But here, the king can have no worries, and White can quietly place his pawns on light squares, restricting the enemy bishop. Meanwhile, the knight is ready to head to the weak square in Black’s camp, namely c5.

More chances of a successful defence were offered by 18...Kf7, maintaining the tension on the queenside