Abstract: Disclosed is a method of sealing a container with a liquid, the container including a body with an opening at at least one end and including at least one sealing plug, designed to seal the opening after filling, the filling defining a free surface S for filling, the filling having allowed a head space to remain in the container. The method includes: introduction of at least one rod parallel to an inside wall of the body of the container; mechanical insertion of the plug in the body, along the at least one insertion rod, generating at least one channel C, the air of the head space being evacuated between the plug and the rod; and withdrawal of the at least one rod while leaving the plug in place at the level of insertion of the preceding step. Also disclosed are the associated device and the industrial production line.