Patrick Mahomes Sr. Had Open Can Of Beer In Car Before DWI Arrest, Cops Say

Authorities claim Patrick Mahomes' father was driving around with an open can of beer in his car before he was arrested for DWI on Saturday night.

The allegation is spelled out in an arrest affidavit from the Smith County Sheriff’s Office ... according to the New York Post.

The outlet reported Monday that in the docs, an officer wrote Mahomes Sr. was found with an open, 16-ounce Coors beverage in his center console after he was pulled over around 8:30 PM in Tyler, Texas.

The officer added that Mahomes Sr. told them during the stop he "had a few beers while watching a game at a local bar" before he got behind the wheel.

Officials wrote in the docs they initially pulled over Mahomes Sr. after they discovered his car had expired tags after he was seen driving slower than the rest of traffic in the area.

The arresting officer alleged Mahomes Sr. failed field sobriety tests once they got him out of his vehicle ... writing in the docs, "I believed Patrick was impaired to a perceptible degree while operating a motor vehicle in a public place."

Mahomes Sr. was ultimately booked on a felony charge of driving while impaired. It's his third DWI -- and if he's convicted this time, he's facing up to 10 years behind bars.

Mahomes Sr. will, however, still be allowed to travel to watch his son play in the Super Bowl this weekend ... TMZ Sports has learned no travel ban was imposed on him as part of the conditions of his bond -- although it remains unclear if the Chiefs quarterback will now want him in attendance.