Maurizio Sarri has confirmed that Gonzalo Higuain is a doubt for Napoli's trip to Verona on Sunday.
The striker has scored nine goals in 12 Serie A appearances this term, but returned from international duty with Argentina "very tired".
Higuain was withdrawn after 70 minutes as Gerardo Martino's side picked up their first win in World Cup 2018 qualifying with a 1-0 triumph over Colombia in the humidity of Barranquilla on Tuesday.
The Napoli coach admitted the former Real Madrid man will need to be assessed before deciding if he will be fit to feature at the Stadio Marc'Antonio Bentegodi.
"We will evaluate the condition of Higuain. He played in the heat, had a long journey and he seemed very tired," Sarri said on Saturday.
"We'll see in training if he has been able to recover and hopefully tomorrow he'll be in decent condition.
"Our plan was to use him part-time, but the injury situation is forcing us into different decisions."
Manolo Gabbiadini and Dries Mertens returned injured, leading Sarri to question the importance of international friendlies.
"It does punish teams who have a lot of international players, as they travel all over the world for often pointless matches," he continued.
"We are particularly disappointed to lose Gabbiadini because at this stage of the season he is essential, as is Dries."
After 12 fixtures, Verona are the only Serie A side yet to secure a win, but the 56-year-old is not underestimating Andrea Mandorlini's men.
"Verona are a much better side than their position in the table would suggest, so I'm sure they will recover and it'll be extremely difficult for us," Sarri added.