Versatility is the key to this Mancunian former England Under-21 international. Indeed it's this that may have prevented him winning a full England place before the 2000/01 season.
Joined West Ham in January 1998 after languishing with Queens Park Rangers in the First Division, but his performances in the Premiership had won him many admirers.
He moved to Upton Park in a £2m deal that saw Iain Dowie and Keith Rowland move in the opposite direction. He started his career as a winger at Blackpool but can play at striker, midfield or wing-back.
Sven Goran Eriksson called him to the England squad in October 2001 for the World Cup qualifier against Greece - his last call-up had come in February the previous year.
Eriksson again called on Sinclair for the game against Sweden in November 2001 when he finally made his debut coming on as a substitute for Darren Anderton.
Surprisingly handed in a transfer request early in the 2001/02 campaign and it looked as though he would move on. The player was unhappy with the club's ambition and he was strongly linked with a £10million move to Sunderland.
Continued his fine displays on the pitch and was tipped to make the England squad for the World Cup.
An injury to Newcastle star Kieron Dyer on the last day of the season saw Sinclair put on standby for the squad. He flew out to Dubai for the club's training camp and then on to Japan for the warm-up games.
Failed to shine in those games and in the end England stuck with Dyer and the West Ham star flew back to England.
However, within a matter of hours Danny Murphy was injured and Sinclair didn't have time to unpack his bag before the call came for him to jump back on a plane.
Was not a popular choice among the public, but all that changed when he replaced the injured Owen Hargreaves after 19 minutes. Sinclair was an inspiration - dangerous in attack and tracking back to defend - as England recorded a famous 1-0 win. The performance would earn Sinclair a starting place for the remainder of the tournament.
On his return, after the Hammers had finished seventh in the Premiership, the player signed a new contract and pledged his future to the Upton Park club. By then he had played 165 games for the club, scoring 29 goals.