Vidal set to miss Australia clash
Reports from Chile's training session in Belo Horizonte on Monday claimed Vidal did not run during the 15 minutes media were allowed to observe, while the Juventus midfielder only kicked the ball with his left foot.
The Santiago-born midfielder also spent part of the session's open period sitting on a bench watching his teammates train.
Vidal underwent minor surgery on his right knee to repair a damaged miniscus on May 7 after helping Juventus seal the Serie A title.
The procedure was intended to allow the versatile, energetic star to play without pain in Brazil, however, his rehabilitation has not proceeded as quickly as expected.
The 27-year-old came on in the 77th minute of Chile's 2-0 friendly win over Northern Ireland on Thursday and the brief cameo appears to have done him no favours.
Inflammation prevented Vidal from any meaningful involvement in training on Monday, prompting reports he could also be in doubt for Chile's other Group B matches against Netherlands and Spain.
If that proves to be the case, he could be cut from the squad altogether.
Jorge Sampaoli's men face Australia at the Arena Pantanal in Cuiaba on Friday and they have until 24 hours before the game to replace Vidal in the squad for the tournament.