CHICAGO: Manchester United, missing many of their big names, began training for their North American tour Wednesday with an hour-long workout at the Chicago Fire`s Toyota Park ground.

Some 1,500 fans turned out to watch the training session, which took place in 90-degree heat.

The English Premier League giants open their tour in Toronto on Friday against Celtic.

They take on two Major League Soccer sides - Philadelphia Union at Lincoln Financial Field on July 21 and the Kansas City Wizards at Arrowhead Stadium on July 25 - before facing the MLS All-Stars in Houston on July 28. They then travel to Guadalajara to play Chivas.

It`s Manchester United`s third pre-season trip to North America since Sir Alex Ferguson became manager in 1986.

Ferguson is without club captain Gary Neville due to a calf problem, while Rio Ferdinand is still sidelined with the knee injury he suffered just before the World Cup.

Michael Owen is unavailable as he recovers from a hamstring injury and midfielders Antonio Valencia and Anderson are also ruled out with ankle and knee problems respectively.

Owen Hargreaves, who has been hampered by a series of knee problems and will miss the start of the season after suffering a new injury setback, completes the list of Ferguson`s walking wounded.

Wayne Rooney, Michael Carrick and Nemanja Vidic were left at home to recover after playing in the World Cup.

BDST: 1448hrs, July 15, 2010