Sithole, 22, has enjoyed a breakout season in the Portuguese top-flight with 25 league games as he helped his side finish 10th in the 18-team division.
Featuring in a defensive midfield role, 'Yaya' and compatriot Thibang 'Cafu' Phete played integral roles in their resurgence up the table in the second half of the season.
Under the guidance of former Portugal midfielder Petit, Sithole has finally lived up to the enormous potential that saw him earn a move from the KZN Academy to Sporting Lisbon back in 2017 as a teenager.
snl24.com/kickoff understands the Lille have identified him as a possible replacement for Boubakary Soumare who's set to join Leicester City in a deal worth a reported €23-million after winning the French top-flight last month.
"Lille and a club in Germany find him as an attractive investment at his current age and have seen his incredible potential, they called him the new William Carvalho when he came to Sporting, he's that type of player," a source told this website.
"None of them has formally approached his club yet but it's going to be an interesting off-season for the player as he plays in a position which many clubs are looking for."
According to leading Portuguese publication A Bola, RC Strasbourg and Lorient are also amongst the clubs that have identified the towering midfielder whose contract expires in 2024 as an off-season transfer target.
Sithole featured 33 times for Belenenses in all competitions and was recently called up to the South Africa Olympic training squad that was set to travel to the United Arab Emirates.
However, his selection in David Notoane's final Tokyo 2020 squad is in doubt due to Covid-19 travel restrictions.