The 24-year-old has endured a disastrous debut campaign since completing a £6.2million move from Swansea last summer, starting just two Premier League games for the Citizens.
Sinclair penned a four-year contract and more than quadrupled the £10,000-a-week salary he earned at the Liberty Stadium, but has already grown frustrated at the amount of time spent kicking his heels on the substitutes' bench.
The Manchester City star's frustration is believed to have alerted the likes of Everton and Aston Villa who are ready to offer Sinclair an escape-route if he decides to leave when the transfer window reopens on July 1.
But, according to the Daily Mirror, Sinclair would prefer to agree a temporary move, in the hope that Mancini will leave the club before the end of his current deal - that runs until 2016 - paving way for him to try and establish himself at Manchester City.
West Brom are also in the running for the young forward if the Daily Express is to be believed, with Baggies boss Steve Clarke ready to lure Sinclair - who earned four caps for Great Britain at the London 2012 Olympic Games - to The Hawthorns next season.