Shid timing with this problem. And the worst is that he doesnt know whats going on...so its not a matter of "lets just rest him".
Something is going on and shuld be treated asap..but with the world cup arund the corner... im pretty sure Vidal will go beyond his limits and this could be an incoming injury.
He has water in his knee, he knew what's going on
"Water on the knee is a general term for excess fluid accumulation in or around your knee joint. Your doctor may refer to this condition as an effusion (uh-FU-zhun) in your knee joint.
Water on the knee may be the result of trauma, overuse injuries, or an underlying disease or condition. To determine the cause of water on the knee, your doctor may need to obtain a sample of the fluid to test for infection, disease or injury.
Removing some of the fluid also helps reduce the pain and stiffness associated with water on the knee. Once your doctor determines the underlying cause of your water on the knee, appropriate treatment can begin."