Two 18-year-old men from Oxford and Reading were arrested on Saturday on suspicion of causing grievous bodily harm with intent.
They have both been released on police bail until 3 October.
The arrests are in connection with an incident on Friday (4/9) just after midnight, when a 19-year-old man was attacked near to the children’s play park within the playing fields between Croft Road, Rippington Drive and Old Marston Road.
The victim remains in hospital in a serious condition.
Investigating officer Detective Constable Vicki Reynolds of Oxford CID, said: “This was a particularly violent assault and has left a teenager with extensive injuries.
“Thankfully, following scans, he does not have a broken neck, but has sustained a fractured skull, a bleed on the brain a broken rib.
“I am appealing to anybody that witnessed the incident or can help this investigation in any way to please get in touch with police.
“I’m particularly keen to hear from anyone who may have CCTV or doorbell camera footage in the surrounding areas of the park to see if it has captured two men walking around the estate between 11pm on Thursday evening and 1am on Friday morning.
“Anyone with any information should call the 24-hour non-emergency number 101, quoting reference number 43200276401.