8:20 PM PT -- Cops tells TMZ ... Young knocked out the man he was fighting by punching him in the face. We're told the man -- who Young knows -- was transported to the hospital and later released.
Former NFL wide receiver Titus Young was arrested in Compton last week after getting into a fight with another man ... and he's still in jail ... cops tell TMZ Sports.
According to the Los Angeles County Sheriff's Dept ... cops received a call about a battery on Tuesday, July 8th at 3:40 PM. Cops have not revealed the identity of the alleged victim, or what the fight was about.
Young was arrested the following day -- and hauled to a nearby station where he was booked for felony battery.
Bail was set at $105K ... he's still behind bars.
It's the latest legal problem for Young -- who's been arrested several times over the past two years.
Young, who was drafted by the Detroit Lions in 2011 -- was cut by the St. Louis Rams in February 2013 -- and it seems his once promising career is over.
Young's father has previously said his son has a severe mental disorder and needs help ... but it appears Young has not received the treatment he needs.