The 26-year-old goalkeeper, who only joined the Saints from Crystal Palace this summer, has been called into Sam Allardyce's Three Lions squad for the weekend's opening World Cup qualifier against Slovakia following an injury to club mate Fraser Forster.
"One man's misfortune is another man's opportunity," said Le Tissier on Sky Sports.
"Alex McCarthy, who's only played a handful of minutes for Saints in pre-season, has got himself a chance in the England squad.
"He must be pinching himself. It's fantastic news for Southampton - that we've got such a capable deputy for Fraser."