Mixing vessel that is designed to accommodate biopharmaceutical contents for the purpose of the mixing thereof, comprising: ▪ A flexible container, comprising: ∘ A wall that has a lower part, a lateral part, and an upper part, delimiting an interior space that can accommodate a certain amount of the contents, ∘ One or more ports for introducing contents or components (C1, C2...) of contents into the container, working with one or more introduction openings provided in the container, ∘ At least one port for draining the contents, working with at least one drain opening, ▪ Means for mixing the contents, comprising: ∘ At least one shaft, able to be driven in rotation by motor means and to drive in rotation at least one mixing element, ∘ At least one bearing with which one end part of the shaft works, ∘ At least one mixing element, able to stir the contents, located in the interior space, characterized by the fact that it comprises at least one combined introduction/upper bearing port (5+11 a) having a rigid flange: ∘ Provided with an introduction passage in fluid communication with the interior space, on the one hand, and with the exterior of the container, on the other hand, ∘ Attached in a rigid and airtight way to the upper part of the container wall around an introduction opening, with the introduction passage and the introduction opening being in fluid communication, ∘ Supporting - from the interior side - an upper bearing (11 a) that is located in the interior space, adjacent to the introduction passage without preventing the fluid communication between the introduction passage and the introduction opening. ▪ A flexible container, comprising: ∘ A wall that has a lower part, a lateral part, and an upper part, delimiting an interior space that can accommodate a certain amount of the contents, ∘ One or more ports for introducing contents or components (C1, C2...) of contents into the container, working with one or more introduction openings provided in the container, ∘ At least one port for draining the contents, working with at least one drain opening, ∘ A wall that has a lower part, a lateral part, and an upper part, delimiting an interior space that can accommodate a certain amount of the contents, ∘ One or more ports for introducing contents or components (C1, C2...) of contents into the container, working with one or more introduction openings provided in the container, ∘ At least one port for draining the contents, working with at least one drain opening, ▪ Means for mixing the contents, comprising: ∘ At least one shaft, able to be driven in rotation by motor means and to drive in rotation at least one mixing element, ∘ At least one bearing with which one end part of the shaft works, ∘ At least one mixing element, able to stir the contents, located in the interior space, ∘ At least one shaft, able to be driven in rotation by motor means and to drive in rotation at least one mixing element, ∘ At least one bearing with which one end part of the shaft works, ∘ At least one mixing element, able to stir the contents, located in the interior space, ∘ Provided with an introduction passage in fluid communication with the interior space, on the one hand, and with the exterior of the container, on the other hand, ∘ Attached in a rigid and airtight way to the upper part of the container wall around an introduction opening, with the introduction passage and the introduction opening being in fluid communication, ∘ Supporting - from the interior side - an upper bearing (11 a) that is located in the interior space, adjacent to the introduction passage without preventing the fluid communication between the introduction passage and the introduction opening.