Roberto Martinez has admitted that he is being 'extra cautious' with Amadou Onana after arriving for Belgium duty with a knock.
The midfielder has made an eye-catching start to his Everton career since joining from Lille for a fee that could reach £33.5 million.
Onana, 21, has made seven appearances for the Toffees so far and established himself as a regular starter in Frank Lampard's engine room.
Onana made a breakthrough into the Belgium senior squad in June and has again been called up for the latest international break.
The Red Devils play Wales in the Nations League this evening.
However, Belgium boss Martinez has revealed Onana suffered a setback playing for Everton in their 1-0 victory over West Ham last weekend.
A late decision on whether he will play against Wales will be made - although Martinez sees Onana as an 'important player' in his squad.
What’s been said
Speaking at his pre-match press conference, the former Everton manager said: "He had a knock. Amadou arrived in camp from his last game with a knock with his club.
“We have to be extra cautious. Today (Wednesday) will make a big difference and in the next 24 hours, we will make a decision based on that.
“He will be involved. I don't know yet if we need to be aware of that or not.
“Amadou had a really good, impressive camp in June from behind the scenes and he's ready to start on the pitch (for Belgium in general).
“Football has changed a lot with the five subs. I would start encouraging everyone to start seeing teams with the 15 players who will be in the outfield positions.
“It's not as much about the starting XI as it used to be. Probably making decisions on the starting line-up probably had bigger consequences than it does now.
“How many times do we see players not play 90 minutes anymore? We see 60-30, 60-30, 70-20 - a lot of sharing with the five substitutes.
“That, for me now, I see Amadou Onana as an important player in the squad - starting or not starting games.
“What I consider is that he is ready to give us a lot.”