Flawed composition?

Originally posted by DeepThought
1. ... Kd5 and 4. ... Kd5.

Okay.

After 1.Kd2 Kd5 2.Kd3 f6 3.Ke2, 3...Ke4 is a blunder.

Black plays 3...Ke6, and I still see no way for white to outflank, even though it seems that white should have an advantage.

The Ke4 blunder is given in the solution as move 5 where I found the problem: http://dejascacchi.altervista.org/exercises.htm (Pawn Endings I)

The solution given is 1.Kd2 Kd5 2.Kd3 f6 3.Kd2 Kd6 4.Ke1 Kd5 5.Kf2 Ke4 6.Ke2 Kd5 7.Kf3 Kc6 8.g4 +-

If black plays 5...Kc4 here, I see no way for white to make progress.