The rebels had kept the army pinned down in two military bases near Maarat al-Nauman, but now the military has escaped and could recapture the main route into Aleppo, the British newspaper The Guardian reported.
Aleppo, Syria's largest city, is caught in a stalemate between rebel and loyalist forces.
"We will see now what happens but if the rebels can push back the regime, they can avoid a major setback," Rami Abdel Rahman of the Syrian Observatory for Human Rights said. "If the regime is able to hold this opening it could take back the whole road and that will have major strategic consequences."
Also Monday, the Syrian National Coalition said a loyalty pledge between al-Nusra Front, a growing force within Syria's rebel opposition, to al-Qaida leader Ayman al-Zawahiri is worrisome.
Expressing concern about recent statements about the "affiliations and ideologies" of some factions within the rebel forces, the coalition urged Jabhat al-Nusra, as al-Nusra Front also is known, "to stay within the ranks of nationalistic Syrians" in fighting President Bashar Assad's regime, The Guardian reported.
Al-Qaida's Iraq branch said Sunday it was formally allied with Jabhat al-Nusra, an increasingly key force within the Syrian rebels.
"Since its inception, the Syrian Coalition has worked to achieve the aspirations of the Syrian people," Syrian National Coalition said in a statement. "Therefore, we strongly reject any position that does not reflect the spirit of Syria's revolution for freedom and dignity. We stand against any forces that may inhibit the Syrian people's choosing of their own future."
Syria's peaceful opposition devolved into an armed struggle and Jabhat al-Nusra has become a part of armed rebel forces fighting against the Assad regime, the statement by the umbrella organization for Syrian opposition groups said.
Syrian opposition group Local Coordination Committees reported shelling in the Damascus suburbs of Jobar, Hazeh and Khan Sheih Monday. No details were provided.
The Syrian Network for Human Rights, another activist group, said 126 people were killed Sunday, including 37 in Damascus. The Syrian Observatory for Human Rights, a British-based monitoring group, reported 130 people were killed.
Reports of violence and death tolls can't be verified because the Assad regime has severely restricted access by foreign journalists.
The Guardian reported Jordan has agreed to head a Saudi Arabia-led push to arm rebel groups through its borders into southern Syria, which coincides with the transfer more than $1 billion from Riyadh to Amman.
Jordan's role as a channel for arms has emerged during the past few months as Saudi Arabia, other Gulf countries, Britain and the United States have increased backing of some rebel groups trying try to stop advances by al-Qaida-linked groups within their ranks. Before now, Jordan's King Abdullah has opened his country's borders to refugees and defectors only.