Influential midfielder De Jong walked down the tunnel clutching the back of his leg inside the opening half hour of Saturday’s Eredivisie game, which Ajax led 1-0 through Klaas-Jan Huntelaar.
Huntelaar would go on to net a hat-trick as Ajax earned a comfortable 6-2 win on the day.
But the bigger picture is not so rosy, with De Jong now looking like a possible absentee for Tuesday's trip to Turin.
Ajax boss Erik ten Hag attempted to play down fears after the game, suggesting De Jong came off as a precaution.
"Frenkie's hamstring was playing up and we didn't want to take any risks," Ten Hag said.
Ten Hag’s side claimed a 1-1 draw at the Johan Cruyff ArenA this week, with David Neres cancelling out Cristiano Ronaldo's first-half opener.
De Jong established himself as one of the most sought-after midfielders in world football thanks to superb performances for club and country, and the 21-year-old will join Barcelona at the end of this season in a deal worth €86 million.The current season also saw him break into the Netherlands set-up, where he has picked up seven caps to date since making his debut in September 2018.