Sinclair said: "It was nice to see the England manager here, watching the English lads in the team.
"It's great for us because if we can keep performing, then we can get the call. The England senior squad is definitely the next step for me.
The Under-21s international also feels that he can be a surpise selection in England's Euro 2012 squad.
"I'm not surprised at all that I'm not on the Olympic shortlist because I want to get in the squad for the Euros. If I can be a late runner for the Euros, I'll be happy."
Sinclair moved to Swansea for £1m in 2010 from Chelsea.