Paul Stirling and Andrew Balbirnie both hit centuries in the shock victory.
David Willey added a rapid half-century at the end of the innings.
The opener scored 82 off 41 balls in a four-wicket win at Southampton.
David Willey and Sam Billings rescued England after a middle-order collapse.
Injury to his team-mate has given another Kent player a chance to impress.
The seamer was dropped for England’s victorious World Cup campaign last summer.
David Willey and Reece Topley are back in the fold for the three matches.
Willey had been involved throughout the four-year build-up to last year’s World Cup but was left out in favour of Jofra Archer.
Reece Topley also recalled four years after his last appearance.
Morgan explained in May that “more time” is needed before Hales is integrated back into the side.