Originally drafted by Real Salt Lake in the 2005 MLS Supplemental Draft, Knowles played two seasons in MLS before joining the Timbers. In Portland, Knowles was a three-time USL First Division all-league selection and helped the Timbers claim the Commissioner’s Cup in 2009 as the league’s regular season champion. In total, he played in 77 games for the Timbers, which ranks among the club’s second-division career leaders, and was named a finalist for the league’s Defender of the Year award in 2007. Following the 2008 campaign, he was voted by fans as the Supporter’s Player of the Year.
From Auckland, New Zealand, Knowles anchored Portland’s backline in 2007, which allowed the fewest goals (18) in a single season during the Timbers 10 seasons as a second-division side. He also played a key role in the Timbers’ USL First Division record-setting 24-game unbeaten streak in 2009. Knowles played the final season of his playing career in the North American Soccer League with the Montreal Impact in 2011.
Knowles had a standout collegiate career at the University of Akron, where he was a two-time All-Mid-American Conference first-team selection. He led the Zips to a pair of conference championships (2002, 2004) and four straight NCAA tournament appearances (2001-04).