The influential Cedars skipper will miss the side's opening qualifiers after their shock run to the final round of World Cup qualifying for the first time in the nation's history
The 31-year-old former Koln and Hamburg midfielder suffered the injury on the weekend in Shandong Luneng's 0-0 draw with Shanghai Shenhua in China's Super League.
The club confirmed Antar had sustained inflammation of the knee ligaments, meaning he'll miss the Cedars' opening three qualifiers after their surprise run to the final round of World Cup qualifying in Asia.
Lebanon, who are ranked 128th in the world and have never reached this stage of qualifying, are due to open their final round campaign at home to Qatar on June 3.
The Cedars host Uzbekistan on June 8, before taking on South Korea in Goyang four days later. Lebanon are also grouped with Iran.
Antar missed Lebanon's final third round qualifier which was a shock 4-2 defeat to UAE.