Shaun Udal, the Middlesex captain, was knocked unconscious against Northamptonshire in the County Championship match, at Wantage Road, on Thursday.
The incident occurred in the fifth over of the day when Udal was struck on the back of the head as he tried to avoid a bouncer from South African allrounder Johan van der Wath. He was unconscious for around six minutes and an ambulance was called while he was treated by the physiotherapists.
Paramedics and a local doctor then assessed Udal on the pitch before he was driven off the ground.
Play was suspended for almost half an hour as Udal was treated on the pitch, but he was able to recover in the dressing room rather than hospital.