Chargers' Khalil Mack Sustains Gruesome Elbow Injury During 'Monday Night Football'

Another win for Khalil Mack against his former team cost him quite a bit ... as the Chargers superstar sustained a gnarly arm injury in the big "Monday Night Football" victory over the Raiders.

The 34-year-old -- who was once traded by the Silver and Black early in his NFL career -- got hurt in the first half of the matchup at Allegiant Stadium in Las Vegas ... when he was trying to tackle Tre Tucker.

The pass rusher went to go wrap up the wideout, but his Bolts teammate collided with him right at the same time -- and the force of the blow appeared to dislocate his elbow immediately.

Mack raced off the field holding his arm in a heap of pain, and he was eventually ushered to the locker room for X-rays.

He did not return to the game -- but he was seen on the sideline in a sling, cheering on L.A. as it cruised to a 20-9 victory.

There's so far no word on his availability going forward ... as head coach Jim Harbaugh said more testing needs to be done.

"See where that takes us," he said.