Striker Tom Pope scored a late goal as the Valiants were defeated by Championship side Bolton Wanderers.
Vale started with new loan signing Freddie Veseli but were stunned as the visitors took the lead after just six minutes through Matt Mills.
Vale nearly struck back immediately through Chris Lines before Sam Johnson made two good saves.
Then Marshall and O’Connor had chances as Vale pushed for an equaliser but it remained 1-0 to the visitors at half-time.
Vale made changes at half-time but Wanderers doubled their lead fifteen minutes from time through Jermaine Beckford.
Vale pulled one back through Tom Pope with seven minutes to go and Louis Dodds almost snatched an equaliser in the last minute, but the visitors held on to win this friendly encounter.
Vale first-half: Johnson, Veseli, Robertson, McGivern, Dickinson, Birchall, Brown, O’Connor, Lines, Marshall, Williamson
Vale second-half: Neal, Yates, Robertson (Smith), Duffy, Dickinson, Daniel, O’Connor, Jennings, Lloyd, Pope, Dodds