 He has played professionally in South Africa, the Netherlands and Belgium for Ajax Cape Town, Ajax and Lierse.Claasen was released by Lierse in April 2013, and subsequently went on trial with Premier League club Everton the same month.Claasen then went on trial with newly promoted Premier League club Hull City in July 2013, initially under the pseudonym of "James Armstrong" for a match against Winterton Rangers, where he scored one goal, before his actual identity was revealed two days later.