England have taken a step towards igniting their attack by picking Alex Mitchell at scrum-half for their crucial World Cup opener against Argentina in Marseille on Saturday.Mitchell was omitted from the original 33-man squad named by Steve Borthwick only to be given a reprieve when Jack van Poortvliet suffered a tournament-ending ankle injury.Having impressed on his first Test start against Fiji, the 26-year-old has retained half-back duties with the aim of adding zip to England's game, while Danny Care provides support from the bench.Tom Curry makes his first appearance under Borthwick and his maiden outing at any level since Sale lost to Saracens in the Gallagher Premiership final in May after being given the nod at openside.Curry has been struggling with an ankle injury sustained during training in early August but in an indication of his influence on England, he has been thrust straight into the back row.Argentina's Juan Cruz Mallia returns at full-back for the Pool D clash as coach Michael Cheika opted for six forwards on the bench.Mallia is part of a back three with goal-kicker Emiliano Boffelli and Mateo Carreras on the wings and a powerful midfield of Santiago Chocobares and Lucio Cinti.Santiago Carreras is at fly-half and Gonzalo Bertranou gets the nod at number nine in what has been Cheika's preferred half-back pairing this season.The team is captained by hooker Julian Montoya, who packs down with props Thomas Gallo and Francisco Gomez Kodela.Montoya was Argentina's leading try-scorer at the 2019 World Cup and six of his 11 career tries have come at global tournaments.The second row is made up of fit-again Matias Alemanno and Tomas Lavanini, who last played as a pair at the World Cup in 2015.Former captain