At the beginning of his career at Manchester City, he played on the left wing, where he had performed for England at the 2002 FIFA World Cup. However, the departure of Shaun Wright-Phillips presented the opportunity for Sinclair to play on his preferred right wing.
Sinclair was released by Manchester City at the end of the 2006-07 season. And on 10 July, 2007 he joined Football League Championship club, Cardiff City. He began the season as a first team player, scoring his first Cardiff goal on 24 September in a 4–2 win in the Carling Cup over West Bromwich Albion. Early on in the season, he suffered from a build up of fluid in his knee and underwent two operations on the injury which ruled him out until mid-February. He made his return on 16 February, 2008 coming on as a late substitute in a 2-0 FA Cup victory over Wolverhampton Wanderers.
On 12 April 2008, Sinclair faced his first club, Blackpool, for the first time since leaving them fifteen years earlier. Sinclair scored Cardiff's second goal in a 3–1 win. However, he refused to celebrate his goal. On 17 May Sinclair made an 86th minute substitute appearance in the 2008 FA Cup Final at Wembley Stadium which Cardiff lost 1–0 to . However, four days later it was announced that his contract with the Bluebirds would not be renewed for the forthcoming season and he was released.
Football: If We Win Cup We'll Party All Summer If We Win Cup We'll Party All Summer Says TREVOR SINCLAIR; FA CUP QUARTER-FINALS: CITY OUT TO END 30 YEARS OF HURT MAN CITY V WEST HAM Tomorrow, Kick-Off 8.05pm Live on BBC 1
Mar 19, 2006; Byline: Simon MULLOCK FORGET about Mancunians being 24-hour party people. If Manchester City win the FA Cup, Trevor Sinclair...