The key move. With this sequence, Gelfand blocks the d-file (...Nd6 + ...e5) and at the same time controls the c8-square. Now this prepares the simple Rc2, dominating the file and planning to penetrate along the 7th rank.
With good criteria, Illescas decides to keep the a-file closed, therefore keeping control over the only open file, the c-file.
1...Rxa7 2.Rxc4 b5 3.Rc6! Transformation of positional advantages! Now Black has to decide whether to lose control over the file or to allow White to have a passed pawn.
A mistake, but a human one. Black wants to control c7. It was needed to leave the a7-g1 diagonal open for the queen to dream about a possible counterplay.
White has a clear advantage, thanks to the control of the c-file. Now a possible plan is to penetrate on c6-c7.
Unity Chess Club
Zbynek Hracek Zoltan Almasi Odorheiu 1995 White to move
Take a close look at the pawn structure. What pieces do we want to keep alive on the board?
The knight was threatening to jump to c4 or a4, bothering a lot our pawns on a3 and c3. By eliminating it, White gets a scenario pretty similar to the game Polgar-Anand, where we have a knight that can end up on d5 against a clumsy and passive bishop.
Once the knight arrives to d4, it will protect c3 and will control important squares like b6 or f6. White could then think about continuing to attack on the queenside or bring his forces to the h-file and attack the king.