Robert Pattinson is due to meet Kristen Stewart for the first time since their split, at the MTV Video Music Awards.
The former couple could to face each other in three weeks at a ceremony in Los Angeles.
Despite breaking up, the 'Twilight' film stars are scheduled to present prizes at the annual event.
It would be the first time they are seen together in public since Kristen admitted cheating on him and moved out of his California home.
An MTV source revealed to the Daily Mirror newspaper: ''This event could be a real embarrassment.
''The idea was for them to jointly present awards but that is looking unlikely now.''
The insider continued to explain that standing together in front of an audience could mislead their fans into thinking they had reconciled.
They added: ''If they go up on stage at the same time fans will believe they are united again.
''If Kristen goes up alone the crowd reaction will be astonishing.
''Fans have bought into the romance on and off screen so she could be in for a horrible night.''