After the departure of left-back Theo van Duivenbode in the summer of 1969 to Feyenoord, Krol became a regular player.

When Ajax reached the UEFA European Cup in 1971, and won, Krol did not play because of a broken leg.

In the 1974 FIFA World Cup, in which the Netherlands reached the final, Krol primarily played at left-back.

By the time the 1978 FIFA World Cup came about, Krol had switched to playing as a sweeper and had earned the captain's armband after the retirement of Cruijff.

In his managerial career, he has been head coach of Egypt, and has been assistant manager of the Netherlands (under Frank Rijkaard and Louis van Gaal) and Ajax (under Ronald Koeman).

Krol's return to Zamalek was meant to be a stabilizing presence, the club having gone through several managers in the preceding two seasons.

After that success, he was contacted to lead the Tunisia national team in the play off qualifying to the 2014 world cup against Cameroon.

He quit as the national team interim coach following Tunisia's loss in the World Cup play-off.