Saphir Taider is expected to end his time at Saints little more than three weeks after joining the club.
The Algerian midfielder has failed to settle on the south coast following what was meant to be a season long loan move from Inter Milan.
The 22-year-old has not figured in any of Saints’ three games so far this season and the Daily Echo understands he is keen to tie up a move back to Italy in the coming days, with Sassuolo confident of securing his signature.
Saints are not expected to stand in his way, as it is believed Taider has failed to impress manager Ronald Koeman in training since switching to St Mary’s.
It will leave Saints considering their options still further before the close of the transfer window on Monday night.
Koeman will be keen to ensure he has sufficient cover in his squad.
He wants to sign one or two more players, with a winger being the top priority.
It remains to be seen whether he will feel pressed into action to recruit another body if, as expected, Taider departs less than a month after arriving.