Update: 6:31PM UNHAPPY with his side's performance against Australia, Chiles coach says an improved effort is a must if the South Americans are to beat Spain.
Despite the Chileans beating Australia 3-1 in Cuiaba, Sampaoli said a better showing was a necessity against the superior Spain.
That's despite the Spaniards' embarrassing 5-1 loss to Holland in Salvador that has their World Cup defence teetering on the edge of extinction.
"If we dont make some changes, we will have difficulties when we play teams that are stronger than Australia such as Spain and Holland," Sampaoli said.
"Right now we will play teams that are really, really strong we have to improve many things to stay in the competition.
"I'm sure the game tomorrow will be difficult because the team we're facing are really good.
"I think they could (still) win the World Cup.
"It's true that they lost the first game but I think they didn't deserve losing like that."
The Chileans flagged noticeably against the Socceroos after leading 2-0 early.
"It's understood that Sampaoli may have reconsidered what had been a demanding training schedule before the game in Cuiaba.
He's expected to make at least one change to the side that started against Australia, with midfielder Francisco Silva set to replace playmaker Jorge Valdivia, who scored in the win over the Socceroos.
Not that Sampaoli would confirm it today.
The Argentine-born mentor also wouldnt bite when asked about his strained relationship with sections of the Chilean media.
"I'm here only to speak about sport and football. "I'm not here to speak about other subjects that might help you sell one more newspaper," a prickly Sampaoli said.
But he's believed to be angry about pictures that appeared in El Mercurio newspaper.
Despite Sampaoli conducting closed sessions behind the fortress-like Taco da Raposa II complex in Belo Horizonte, El Mercurio published training photographs that seemingly confirmed Silva's inclusion at the expense of Valdivia, who plies his trade in Brazil with Palmeiras.
Spain coach Vicente Del Bosque is also tipped to make changes, although goalkeeper and skipper Iker Casillas is set to retain his spot despite a horror performance against the Dutch
There have been suggestions that Barcelona trio Xavi Hernandez, Jordi Alba and Gerard Pique are facing the chop, while the place of Manchester City attacking weapon David Silva has also been questioned.
Chelsea striker Fernando Torres wasn't sure if he would be called into the starting team but said it didn't matter who played, with the priority being a Spanish win.
"It's not important whether I play or not. The important thing is that we win," said the much-maligned Torres, who blew a golden second-half chance after coming on against the Dutch.
"If we lose, we'll lose as a team. If we win it will be the whole team, 23 players plus coaches plus everybody else.
"I hope we will be able to win playing in our usual style and at a high level, at the same level that allowed us to win the (2010) World Cup and the (2008 and 2012) Euros.
"If we cannot win like that we have to win any way, because anything else would mean that we would have to go back home."
Midfield star Andres Iniesta said the Spaniards were ready to redeem themselves.
Spain also lost their first game at the 2010 World Cup 1-0 to Switzerland before recovering to win the tournament.
"Its true that we have started in a way that makes it difficult to feel like we felt before that match, but what happened during our first match is something that we must forget," Iniesta said.
"We have to play two more matches (against Chile and Australia) that are like finals.
"We had a similar situation during the last World Cup. We trust in ourselves, I trust my teammates. I think were able to do it."
Chile will meet Spain at 6.30am (Fiji Time) on June 19.