4...c5 5.b5 and White is winning. The plan is simple: pushing a5 and a6. Once the pawn arrives at a6, Black is forced to go ...Kc7 to stop b6. Nd5+, followed by Kc4, just kills the game.
Final maneuver: bring the knight to d4, send the black king to f6, and then White is ready to push b5, creating the killer passed pawn on the a-file.
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Vladimir Kramnik Arkadij Naiditsch Olympiad 2012 White to move
Advantage transformation is one of the most difficult strategical elements to evaluate since it is very painful to get rid of the thing that gives us the advantage, such as a superior piece or passed pawn.
Kramnik gets rid of his powerful bishop and forces Black to decide how to capture. This exchange is very typical in this system.
16...Bxc6 17.d5 Bb7 18.e4 White gets a strong and mobile pawn center and the b7-bishop is completely buried.
The b7-bishop is momentarily dead and to activate it Black would have to weaken his king even further.
Black finally frees the bishop but now his king will be in a pretty shaky situation.
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Vladimir Kramnik Peter Leko Dortmund 2013 White to move
White's position is no doubt preferable, but there is only one move that wins the game for Kramnik at this moment. Can you see it?