The Paris-Saint Germain forward looked in fine fettle while taking part in a warm-up drill but quickly pulled up and was unable to continue.
The injury has left Brazil fans fearing a repeat of the 2014 World Cup, where Neymar's tournament was ended when he suffered a back injury in the quarter-final win over Colombia. For Neymar or any other player for Brazil, the pressure is always there, this is expected.
Neymar was initially in the middle trying to regain possession of the ball but as soon as he made a block with his right foot, he grimaced in pain.
Willian heads into World Cup in Russian Federation having scored 13 goals and provided 12 assists for Chelsea last season, helping the Blues to the FA Cup. He limped as he walked away from the field toward the dressing room, accompanied by a team doctor.
Neymar Jr reacts during a training session at Yug-Sport Stadium on June 19, 2018 in Sochi, Russia.
However, Coutinho said the players did not consider Friday's second Group E game against Costa Rica, who lost 1-0 to Serbia in their opener, to be a must-win match.
Whether this limits his participation against Costa Rica remains to be seen.
Rodrigues said the pain Neymar felt Tuesday was not in the same place where he injured his foot earlier this year.
"Today everyone is better prepared for a World Cup". In 1998, Alan Shearer was fouled a whopping 10 times in England's curtain-jerker against Tunisia. This game is important and we're looking for three points.