Sinclair was the hero of Swansea City with a Wembley hat trick that took them into the Premier League in the Championship play off final.
And he then joined up with England for their Under 21 tournament before being given a longer break by Brendan Rodgers after his extended season.
Speaking to the Evening Post, Rodgers said "Scott had two and a half weeks less than everyone else off because of the European Championship so I've given him extra time before he had to come back
"He meets up with us this weekend and, while he will not be involved in the game at Afan Lido, he will fly out with us to Austria on Monday.
"He will be fine by the time we play Manchester City.
"He has kept himself ticking over and he is really looking forward to getting back playing, so I don't think there will be any problem with his fitness."