Thrill-seekers want another World Cup shock but three times champions Italy believe their path to glory will open up if they successfully negotiate a way out of group G on Thursday.
"We can lose something or take everything," striker Christian Vieri said ahead of their decider with Mexico in Oita.
"We know how important this one match is for us."
Defeat is likely to consign Italy to the embarrassing fate already suffered by defending champions France and pre-tournament favourites Argentina this week -- a first round exit.
Victory would restore the confidence bruised in their surprise 2-1 defeat to rivals Croatia last Saturday and rekindle feelings that this might be Italy's year once more.
"We feel fine physically and we are in a very good condition," said coach Giovanni Trapattoni. "There was some disappointment after the Croatia game but it passed in 24 hours."
Mexico, who need only a draw to assure themselves of a place in the last 16, lead the section with six points. Italy and Croatia are second and third with three points and Ecuador are bottom with none. Croatia meet Ecuador, also on Thursday.
Trapattoni confirmed he plans one playmaker, expected to be Francesco Totti, behind two frontline strikers -- in all probability, Vieri and Filippo Inzaghi.
Trapattoni is waiting on the fitness of defender Alessandro Nesta, who is set to miss out after pulling out of training on Wednesday with a foot problem, and midfielder Cristiano Zanetti.
Mexican coach Javier Aguirre has a full squad to choose from.
Mexico reached the last 16 in the 1994 and 1998 finals, and have looked impressive this year, with Gerardo Torrado and Ramon Morales controlling midfield and the partnership of Cuauhtemoc Blanco and Jared Borgetti leading the line.
"They have no obvious weak spots...Torrado and Blanco are so important to them," said Trapattoni.
Aguirre said: "We have surprised a few people with our performances so far and this team still has more to give.
"Before the tournament, Italy were big favourites to go through and to win this game. But nothing is so certain anymore."
Italy (4-3-1-2): 1-Gianluigi Buffon; 2-Christian Panucci, 5-Fabio Cannavaro, 15-Mark Iuliano, 3-Paolo Maldini; 19-Gianluca Zambrotta, 17-Damiano Tommasi, 6-Cristiano Zanetti; 10-Francesco Totti; 9-Filippo Inzaghi, 21-Christian Vieri
Mexico (3-5-2): 1-Oscar Perez; 5-Manuel Vidrio, 4-Rafael Marquez, 16-Salvador Carmona; 7-Ramon Morales, 6-Gerardo Torrado, 18-Johan Rodriguez, 11-Braulio Luna, 21-Jesus Arellano; 9-Jared Borgetti, 10-Cuauhtemoc Blanco
Referee: Carlos Simon (Brazil)
Jorge Oliveria (Brazil)
Mat Lazim Awang Hamat (Malaysia)