On 13...f5, White opens the position by means of 14.g4!.

There is no defence against the threat of advancing the h- and g-pawns.

Here, Black missed a chance to exploit the white back-rank weakness and the overload of the white queen:

The actual game continued 27...Qf6 28.Bxd3, with a double-edged struggle.

With a winning position.

The white queen not only attacks f6, but also ‘eyes up’ the Ra8. The rook on f8 defends both of these, and cannot cope with the task:

Or 24...Qxf6 25.Qxf6 Rxf6 26.Bxe5.

Winning.

The queen at c5 fulfils many functions, defending the Be3 via the diagonal, the pawn d6, and the Ra7. First, White deflects the king, drawing it to a vulnerable position:

And now, he exploits the overloading of the queen: