American born Zak made his senior debut for Liverpool against Millwall in the Carling Cup tie at The Den during the 2004/5 campaign. However, he was finding it difficult to establish himself as a regular in the first team set-up at Anfield and jumped at the chance of a loan move to The Den, with the prospect of playing Championship football. His made an immediate impact in the home game against Leeds United on 26th November 2005, and was virtually ever present thereafter, extending his loan period until the end of the season.
Everyone at Millwall was delighted when he elected to move to The Den on the three year contract in June 2006. Unfortunately an injury sustained in the home game with Northampton in September kept the young defender sidelined for the rest of the season. Zak won his fitness battle after a lengthy absence, and following injury to Richard Shaw in November 2007 established himself as the number one partner for skipper Paul Robinson at the heart of the defence. In spite of further injury setbacks he returned to have an outstanding end to the 2008/9 campaign in which promotion was narrowly missed.
He elected not to sign a new contract in the summer of 2009 and was transfer listed. Following a hip operation he is expected to be out of action until November.

Previous club: Liverpool
Lions debut: v Leeds United (H) 26th November 2005