The Juventus midfielder has recovered well from his knee injury, according to his coach, and is likely to feature against Australia in Group B opener
By Peter Staunton in Cuiaba
Vidal played 15 minutes in the 2-0 win over Northern Ireland last week; his first outing since undergoing knee surgery after his club side Juventus claimed a third successive Serie A title.
There were widespread fears in the build-up to Chile's first match of the tournament that Vidal would not be passed fit but Sampaoli is optimistic that his 54-times capped talisman will be available.
"The decision will be taken in the next few hours," he told the press. "His injury was rather complicated. He did what he could to get better. His physio has done a marvellous job and there is a high possibility for him to be there.
"Of course, there is an athletic side to him. If he was not as strong, he would not be at this level. We hope he will be able to play."
Despite recovering well in time for the World Cup, Sampaoli did admit that the 27-year-old was short of match practice.
"The clinical phase is over," he said. "The diagnosis was clear. He had the treatment. He is up to his normal levels the last three or four days.
"Next is the football phase. We believe he does not yet have that same rhythm. But we should not forget the personality of Vidal. He is extremely important and he really wants to play. The final decision will be taken by us.
"On Vidal, this chapter is closed. He, as a player, will know if his knee will support the intensity of this competition."
Sampaoli paid tribute to his opposite number, Australia coach Ange Postecoglou, on the eve of their encounter and admitted his side face a tough assigment against the Socceroos with holders Spain and the Netherlands to come.
"Australia are a difficult team," he warned. "They have changed their set-up and come here without pressure. We must face nervousness, stress and pressure. They don't have that pressure.
"Their style of play can be rather complicated if we're not having a good day and not functioning as a team. I think it's going to be a really tough match for us.
"Under the previous coach and in their previous phase they were physical. That's their history. The new coach has trained them differently. Instead of physical, it's going to be a different kind of duel.
"We may find a certain weakness and put pressure on Australia to induce errors. This is how we will approach the match."
Following on from the match in Cuiaba on Friday, Chile face Spain in Rio de Janeiro next Wednesday before rounding off the group stage against the Dutch on June 23 in Sao Paulo. Chile are regarded as a genuine threat to the 2010 finalists and Sampaoli is determined to show that his side is ready to come of age.
"You have to play with the highest possible intensity," Sampaoli added. "We are in a group where we will have to face off against the threat of great players and great teams. We want to go beyond our present performance levels.
"We have to be well prepared. That is essential. Then it is necessary to stand up against any opponent we have. If we played differently, we'd lose our identity. This is a very good moment to evaluate the level of Chilean football."