Born in Myjava, Valach made his official debut as an amateur cyclist at the 1996 Summer Olympics in Atlanta, where he finished sixty-eighth in the men's road race by less than a second behind the peloton leader Abraham Olano of Spain, recording his personal best time in 4:56:48.

[2] During his amateur career, Valach has claimed three Slovak titles in elite national championships (1997 and 1998) until having shown his great talent and passion for sport, he turned professional in 1999 with De Nardi–Pasta Montegrappa.

Competing under a freelance agent, Valach pulled ahead from a vast field of cyclists to dominate the road race at the 2003 Coupe des Carpathes in Poland in 3:57:03.

[4] He had solidified his lead by defeating the Austrian cyclist Michael Pichler at Völkermarkter Radsporttage road race, and also sprinted into a second-place finish at the second stage of Sachsen Tour in 5:52:17, trailing behind Great Britain's Dean Downing by less than a second.

[6] Riding against his teammates Roman Broniš and Matej Jurčo, Valach remained as the only Slovak cyclist to successfully complete a grueling race with a sixty-second-place effort in 6:34:26.