Sarri managed Hysaj while Napoli boss last season before replacing Antonio Conte as Chelsea manager in the summer.
He had been blocked from bringing the Albanian ace to Stamford Bridge having already nabbed Jorginho.
But now it seems Sarri is prepared to make his move with the Sun reporting a £20million bid could be made.
Hysaj’s agent Mario Giuffredi recently suggested that the Blues were still interested in his man.
“I can’t rule out resuming negotiations with Chelsea in January,” Giuffredi told Radio Crc.
“We know there was contact in the summer because Sarri wanted him, and we also know that Zappacosta is not to the liking of the coach.
“We’ll see how it goes, anything could happen.”
Chelsea are thriving under Sarri and the Italian is keen to keep improving.
The Blues inflicted a first defeat on Man City on Saturday, beating the reigning Premier League champions 2-0.
Goals from N’Golo Kante and David Luiz kept Chelsea within touching distance of the top as they now sit eight points behind leaders Liverpool.
Though Sarri believes his side aren’t in the race for the title.
“As I said, always as you know, I think the gap is impossible to cover this kind of gap only in one season,” the Italian said.
“One match – you can play one match, of course. Then in the competition of 10 months it’s very difficult to cover the gap.
“I think they [Man City] are, at the moment, the best team in Europe.
“We won today. But we have to say we were a bit lucky in the first 25 minutes, because they could scored.
“A little bit lucky in the first half and very good second half.”