Duvan Zapata is flying to Finland for a specialist consultation, so surgery could round off a remarkable few months that saw the Atalanta striker close to Newcastle United and hit by repeated problems.
The Colombia international made his comeback as a substitute in the 2-1 home defeat to Cagliari and lasted only circa 15 minutes before limping off again.
It is feared he has suffered a relapse to the adductor tear that had kept him out of action for seven weeks.
Atalanta released a statement confirming he is flying out to Finland for a specialist consultation with Professor Sakari Orava.
Among his previous patients were David Beckham, Andrea Barzagli, Giacomo Bonaventura and Bryan Cristante.
There are concerns surgery could be required, which would effectively end his season early.
Duvan Zapata has played only 23 competitive games for La Dea this season, scoring 12 goals and providing seven assists.
That early campaign form earned him a huge January transfer offer from Newcastle United, believed to be worth at least €40m.
Atalanta had considered it, but ultimately turned down the bid, instead releasing Roberto Piccoli on loan to Genoa.
They had already sold Robin Gosens to Inter and did not want to lose another of their key players.
Like Gosens, Duvan Zapata has spent much of the last few months on the treatment table, so it should ultimately make little difference on the field for coach Gian Piero Gasperini.
Duvan Zapata was one of the most expensive signings ever made by Atalanta, initially on a two-year loan for €14m from Sampdoria in 2018, then purchased on a permanent basis in January 2020 for a further €12m.
His contract only runs to June 2023, so decisions now have to be made about keeping the 30-year-old.