In his first season at Manchester United, Amos became a regular starter for the club's Under-13 team, playing in 19 out of 27 matches in the 2001–02 season.
Amos was named as an unused substitute for the Under-18 side for the first time on 8 January 2005, for a league game against Manchester City.
His first appearance for the Under-18s came exactly nine months later, on 8 October 2005, coming on as a substitute for Danny Rose after starting goalkeeper Ron-Robert Zieler was sent off in a 2–0 defeat to Bolton Wanderers.
He was regularly named as an unused substitute during the 2005–06 season – including for two reserve team matches – but became a frequent starter for the Under-18s in 2006–07 after signing a trainee contract in July 2006.
However, he missed the final of the 2006–07 FA Youth Cup with a dislocated shoulder.

He retained his place in the Under-18 team for 2007–08, in addition to making his debut for the reserve team against Wigan Athletic on 7 November 2007, and during the season he impressed enough to be selected to go on the first-team's 2008 summer tour of South Africa.
Amos was named as a substitute for all three matches of the tour, but did not play.
En route back from South Africa, United stopped off in Nigeria to play against Portsmouth on 27 July 2008, with Amos replacing Tomasz Kuszczak after 76 minutes.
He made his competitive first-team debut on 23 September 2008 in a 3–1 win at home to Middlesbrough in the third round of the League Cup.
On 14 December 2008, Amos travelled to Japan with the Manchester United squad for the 2008 FIFA Club World Cup, having been called up as a late replacement for Ben Foster, who had suffered a hand injury while training.
In his first season at Manchester United, Amos became a regular starter for the club's Under-13 team, playing in 19 out of 27 matches in the 2001–02 season. Amos was named as an unused substitute for the Under-18 side for the first time on 8 January 2005, for a league game against Manchester City. His first appearance for the Under-18s came exactly nine months later, on 8 October 2005, coming on as a substitute for Danny Rose after starting goalkeeper Ron-Robert Zieler was sent off in a 2–0 defeat to Bolton Wanderers. He was regularly named as an unused substitute during the 2005–06 season – including for two reserve team matches – but became a frequent starter for the Under-18s in 2006–07 after signing a trainee contract in July 2006. However, he missed the final of the 2006–07 FA Youth Cup with a dislocated shoulder.
He retained his place in the Under-18 team for 2007–08, in addition to making his debut for the reserve team against Wigan Athletic on 7 November 2007, and during the season he impressed enough to be selected to go on the first-team's 2008 summer tour of South Africa. Amos was named as a substitute for all three matches of the tour, but did not play. En route back from South Africa, United stopped off in Nigeria to play against Portsmouth on 27 July 2008, with Amos replacing Tomasz Kuszczak after 76 minutes. He made his competitive first-team debut on 23 September 2008 in a 3–1 win at home to Middlesbrough in the third round of the League Cup. On 14 December 2008, Amos travelled to Japan with the Manchester United squad for the 2008 FIFA Club World Cup, having been called up as a late replacement for Ben Foster, who had suffered a hand injury while training.
Ben Amos