In August 2007, he received an injury to his knee cartilage and it was expected that he would be unavailable for up to four weeks, but he contracted an infection during an operation on the injured knee that delayed his return for a much longer period. He made his return to first team football in October, and went on to score a headed goal in the 2–1 League Cup defeat by Liverpool at Anfield on 31 October. The 2007–08 season turned into a disappointment for Purse as he was forced out of the side by "Bluebirds" fan favourite Roger Johnson. He also scored several own goals, including a spectacular volleyed pass back that proved too powerful for Cardiff goalkeeper Peter Enckelman. He was also labelled a "muppet" by Burnley forward Andrew Cole, after Purse was sent off for what was deemed a dangerous tackle against Cole, although Cardiff manager Dave Jones defended the player and the ban was later overturned. Purse did not feature in City's FA Cup run to the final at Wembley, and was an unused substitute as Cardiff were beaten 1–0 by Portsmouth.