HOUSTON, Texas (KTRK) -- Ticket sales for England's Manchester United and Manchester City game in Houston on July 20 will be delayed due to the terrible tragedy at Manchester Arena on Monday night.At least 19 were killed and 50 injured after an explosion at Manchester Arena during an Ariana Grande concert.Relevant Sports, the organizer for the Manchester United vs Manchester City game, issued this statement:The two teams are scheduled to take the field at NRG Stadium. This will be the first time the rival teams have played each other outside of England.As two of the top clubs in the English Premier League, Manchester United F.C. and Manchester City F.C. have a long and storied rivalry which dates all the way back to 1902. Sharing the same hometown, the aptly named Manchester Derby has taken place 173 times between the two clubs who boast a combined 24 English Premier League titles, including seven of the previous ten. This match will represent the first Manchester Derby played outside of the United Kingdom in the rivalry's 115-year history.The game will be a part of the International Champions Cup.No new date has been set for tickets to go on sale.