The Englishman’s deal runs until the summer with an option for a further year but he is yet to hear from the club regarding his future.
Sinclair has been a pivotal player for Celtic since signing in the summer of 2016 from Aston Villa. He started by netting six goals in consecutive league games before winning the PFA Scotland Players’ Player of the Year and Scottish Football Writers’ Association Footballer of the Year in his first season.
Despite questions over a dip in form he has hit 35 goals in the last two campaigns, including 17 this term.
He could, however, be allowed to walk away for free this summer if the club opt against taking up the extension in his contract.
With Neil Lennon in interim charge there is uncertainty over the club’s management position in the longer term.
Any new manager will likely have to undertake an extensive recruitment drive with Mikael Lustig, Dedryck Boyata, Oliver Burke, Timothy Weah, Jeremy Toljan and Filip Benkovic some of the names expected to depart at the end of the campaign.