Piet Keizer

With the Dutch national team, Keizer played 34 times, scoring 11 goals. He made his international debut in an 8–0 friendly win against the Netherlands Antilles in 1962. Keizer was selected by Netherlands manager, Rinus Michels, to play for the Dutch squad during the 1974 FIFA World Cup, but only started in the 0–0 draw against Sweden.

Keizer totalled 489 official matches for Ajax, scoring 189 goals between 1961 and 1974, and is a member of the Club van 100 at Ajax, a list of players playing more than 100 official games for the club. He made his debut in the first team on 5 February 1961 against Feyenoord. He played predominantly on the left-wing and with Ajax, he won three consecutive European Cups (1971, 1972, 1973), having lost the 1969 European Cup final to AC Milan. In addition, he won six Eredivisie titles, five KNVB Cups, two European Super Cups, one Intercontinental Cup and one Intertoto Cup. In March 1964, Keizer got seriously injured during a KNVB Cup match against DWS; a critical surgery was needed due to a skull fracture and a blood clot in his brains. In August 1973, under new Ajax manager George Knobel, the Ajax players voted in a secret ballot for Keizer to be the team's next captain, ahead of Johan Cruyff. Just weeks later Cruyff left Ajax to join Barcelona.

Keizer suddenly retired from football in October 1974, shortly after a row over tactics with Ajax manager Hans Kraay.

On 13 June 1967, Keizer married Jenny Hoopman. The couple had two sons. Keizer died of lung cancer in February 2017, after a long illness. Football player and manager Marcel Keizer, who played in the Ajax youth academy and was a manager of the first team in 2017, is a nephew of Piet Keizer.