The Major League Soccer team is signing a midfielder in the twilight of his career who struggled to make an impact after joining United in 2015.
After allowing an own goal in the fourth minute, the Fire lost Johan Kappelhof to a red card in the 11th. It was all downhill from the there.
David Accam scored in the 73rd minute to lift the Fire to a draw with the host Columbus Crew on Saturday.
The match on Aug. 2 will feature the MLS All-Stars against an international team that has not been named yet.
Arturo Alvarez scored his first MLS goal since 2010.
The Fire have been shut out the last two games and four times this season. They have a league-low eight goals.