Activists say Syrian troops and opposition forces are battling for control of a key highway outside Damascus.
The fighting is the heaviest in Damascus since the first rebel push into the capital in July.
Checkpoints on the main artery into the capital have changed hands several times since Wednesday when the opposition fighters started their campaign for the capital, the seat of President Bashar Assad's power.
A rebel fighter told The Associated Press that opposition forces on Sunday overran al-Adnan checkpoint in Jobar, northeast of Damascus.
He spoke on condition of anonymity for security reasons.
The Britain-based Observatory for Human Rights says that while the fight for the highway continues, government troops regained control of the area on Saturday after using fighter jets to bomb rebel positions.