He was found on the pavement by the junction of Tomkinson Road and Clifton Road.
He was found at around 5 am and was taken to hospital with serious injuries and is currently receiving treatment.
Officers want to speak to anyone who may have seen him.
Investigating officer, Det Sgt Richard Walker from Warwickshire Police, said: “Enquiries are currently ongoing to ascertain how the man established these injuries.
“It’s not currently believed he was assaulted but we need to speak to anyone who may have seen him, or who may have any CCTV or dashcam footage in this area, so we are able to establish the exact circumstances.
“If anyone has any information, please call Warwickshire Police on 101 quoting incident number 59 of 8 August.”
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