The planned suspension stems from an alleged incident with an Uber driver in Scottsdale, Arizona, in March 2016.
The league still has not notified Winston of its official decision, and the circumstances surrounding it still could lead to an increase or decrease of the three games, per sources.
One source said Winston could be notified as early as Friday, but others think it will be handed down sometime in the next week, per sources. An appeal could be discussed, but they have proven to be largely fruitless in the past, most recently with Dallas Cowboys running back Ezekiel Elliott, who was suspended six games last August.
Winston would lose $124,000 in base salary for a three-game suspension because his base salary is only $705,000 this season. His base salary for next season is scheduled to be over $20.9 million, reducing the chance he would consider appealing this three-game suspension.
NFL investigator Lisa Friel helped spearhead the investigation that would see the suspension of another NFL star.
ESPN Tallahassee host Jeff Cameron initially reported this week on his talk show that Winston was bracing to be suspended.
Although the alleged incident occurred in March 2016, it did not surface until BuzzFeed reported the accusation in November 2017. The NFL initiated its investigation -- with Friel at the forefront of it -- and the Buccaneers have been waiting to hear from the league.
The league began its investigation in November 2017 when a woman, who identified herself as "Kate," told BuzzFeed that Winston reached over and grabbed her crotch while waiting at a drive-thru at Los Betos Mexican Food at 2 a.m.
Restaurant management told ESPN that they did not have security footage of the drive-thru. No police charges were filed, but the driver did file a formal complaint with Uber. She told BuzzFeed that she wanted to tell the truth "about a powerful man who felt entitled to my body when all I wanted to do was my job." Uber confirmed to ESPN that Winston's riding privileges were revoked, but Winston did not notify the league of the complaint.
Winston denied the allegations and said he believes the woman was mistaken regarding the number of passengers in the car and his location within the vehicle. Former Florida State teammate and Philadelphia Eagles cornerback Ronald Darby said he was also a passenger in the vehicle and corroborated Winston's account, which was that he and Winston were in the vehicle's back seat and that a third person was in the passenger seat. Darby did not identify the name of the third passenger publicly.
The Uber driver's attorney, John Clune, disputed Darby's account, saying that Winston was the only passenger in the vehicle.
Clune also represented Erica Kinsman, a student who accused Winston of sexual assault at Florida State in 2012. The accusations were investigated by Tallahassee police but charges were never filed. Winston was not suspended from the school or disciplined by the football team for the incident. Winston was disciplined on a separate incident, in September 2014, for standing on a table inside the university's student union and shouting a sexually explicit internet meme.
Winston's accuser at Florida State did file a civil suit against him, and he countersued. The suits were settled out of court in 2016 and specifics were not released. Florida State was, however, found culpable in a Title IX lawsuit filed by Kinsman for its handling of her complaint. In January 2016, they agreed to pay her $950,000 but did not admit liability as part of the settlement.
Last month, multiple sources said they did not expect Winston to be disciplined over the Arizona incident. But the case unnerved the NFL and Friel enough that the league is now preparing to hand down a three-game suspension that still could be altered based on any last-minute findings. The decision will come as a major disappointment to a Buccaneers team looking to rebound this season, especially considering the type of behavior that Winston has demonstrated.
Multiple people in and around Tampa have spoken highly of Winston's good deeds within the community. But questions about his maturity and decision-making have followed Winston since his time at Florida State.
If Winston sits three games, or any amount of time, the Buccaneers would be forced to start quarterback Ryan Fitzpatrick, who posted a 2-1 record last season when he was asked to start due to Winston's shoulder injury.
Behind Fitzpatrick is Ryan Griffin, who now figures to be Tampa Bay's backup quarterback for the first part of this season.
ESPN's Jenna Laine contributed to this report.