Manchester City's Fernando in action with Aston Villa's Scott Sinclair
Sinclair, 27, completed a permanent move to Villa Park last summer having played for the club on loan from Manchester City in the second half of the 2014/15 season - but had an up-and-down campaign last season.
Aston Villa's Scott Sinclair in action as Watford's Juan Carlos Paredes looks on
The winger scored six goals in 27 games for Villa, but couldn't stop the club from suffering relegation to the Championship - and his future is now in doubt.
The Daily Mail report that Celtic have made three bids for Sinclair already, but have failed with each of them - and have now had a fourth rejected as well.
Sinclair worked with Bhoys manager Brendan Rodgers at both Chelsea and Swansea City, and having hit 35 goals in 90 games under his tutelage at Swansea, it's a tried and tested relationship between the duo.
Rodgers is therefore desperate to land Sinclair, but has allegedly had a fourth bid - this time worth £2.75m - rejected, with Villa still looking for more money from Celtic.
However, the Daily Mail report that a deal is expected to go through eventually, but a transfer is unlikely to be done by the time Celtic take on Astana in the Champions League on Wednesday.
Meanwhile, The Scottish Sun report that Sinclair is keen on the move, as he wants to reunite with former boss Rodgers - but Villa are playing hardball, as they want "considerable add-ons" if Celtic reach the group stages of this season's Champions League.
Would you like to see Sinclair sign for Celtic this summer?