Nigeria forward Lookman became an Atalanta legend in May when his stunning hat-trick downed German champions Bayer Leverkusen and won the traditionally provincial club their first ever European trophy, a first major honour of any sort since 1963.
However the 26-year-old was not included in the squad announced on Sunday for Atalanta's trip south, where Gian Piero Gasperini's side will begin their league campaign on Monday evening.
Italian media have widely reported that Lookman's representatives have told Atalanta of PSG's interest as the club go through an eventful summer transfer window.
On Sunday Serbia midfielder Lazar Samardzic arrived in Bergamo for his medical ahead of a 20 million-euro ($22 million) move to Atalanta from Udinese, as another of last season's heroes Teun Koopmeiners agitates for a move to Juventus.
Koopmeiners was also not named in the 23-man squad for the Lecce match but Atalanta have as yet refused to agree terms with Juve who are rebuilding their team for new coach Thiago Motta.
Atalanta lost centre-forward Gianluca Scamacca to a serious knee injury earlier this month, causing them to sign his Italy teammate Mateo Retegui from Genoa.
Lookman, who has played 23 times for Nigeria, scored three goals in his country's run to African Cup of Nations final over January and February.
