Messi will star for the good of Argentina - Sampaoli
Messi missed a penalty in his country's opening 1-1 draw against Iceland in Group D and cut an increasingly forlorn figure as they unravelled to 3-0 defeat against Croatia last week.
It means Argentina must beat Nigeria – they have done so four times previously at World Cups – to retain any hope of the Barcelona superstar embellishing his magnificent career with the sport's greatest prize.
"I think that match was complicated for Leo, the structure of the game didn't favour him and he didn't get a lot of balls from the midfield," Sampaoli told a pre-match news conference at Krestovsky Stadium after being informed his star man enjoyed fewer touches of the ball than goalkeeper Willy Caballero.
"If he had the ball less than usual it's because Argentina didn't dominate the match as we did against Iceland.
"We are going to try and improve that and we are sure that is not going to happen tomorrow.
"For the good of Argentina, I am sure Lionel Messi will be touching the ball a lot more than in our previous match."
[SELECCIÓN MAYOR] @Argentina ya pisó la ciudad de San Petersburgo. Así era la llegada de nuestro capitán Leo Messi. #SomosArgentina pic.twitter.com/MT4kB3kJki
— Selección Argentina (@Argentina) June 25, 2018
Sampaoli declined to confirm the identity of his starting XI but wholesale changes – including the restoration of Paris Saint-Germain winger Angel Di Maria and Juventus striker Gonzalo Higuain being preferred to Sergio Aguero – are expected.
One change that seems a safe bet is goalkeeper Franco Armani making his international debut in place of Caballero, whose dreadful error allowed Croatia's Ante Rebic to open the scoring in Nizhny Novgorod.
River Plate keeper Armani flanked his boss at the media briefing and offered warm consolatory words to Chelsea and former Manchester City understudy Caballero.
"I've been sharing my room with Willy, we've been sharing the training sessions and spending time together day after day," he said.
"The situation that has arisen could have happened to any of us. All l did was give him encouragement and supported him.
"I have also had very difficult, similar situations. Those of us who are goalkeepers know how it feels."
Armani added: "He has shown me throughout all this time that he's a great person with a huge heart. He is a great professional
"I have given him my support and encouragement and we have to leave that episode in the past now."