Tom Brady said on Friday he will not ask the U.S. Supreme Court to block his four-game "Deflategate" suspension, ending his fight in a scandal that tested the power of the NFL commissioner and tarnished the reputation of one of the sport's greatest players.

"It has been a challenging 18 months and I have made the difficult decision to no longer proceed with the legal process," the New England Patriots quarterback said in a Facebook post . "I'm going to work hard to be the best player I can be for the New England Patriots and I look forward to having the opportunity to return to the field this fall."

The decision by the four-time Super Bowl champion comes two days after his case was turned aside by the 2nd U.S. Circuit Court of Appeals. Brady's only remaining hope to take the field when the Patriots open the season against Arizona on Sept. 11 had been a stay from the nation's highest court, which accepts about 1 percent of the appeals submitted.

More worrisome for Brady and the Patriots, though, was the chance that he would receive a stay — which would require only the blessing of a single Supreme Court justice, in this case Ruth Bader Ginsburg — only to have the whole court later refuse to hear the case. That could allow the suspension to fall at a more inconvenient time in the season, perhaps including the playoffs.

"This decision was made in the interest of certainty and planning for Tom prior to the New England Patriots season," the NFL Players Association said in a statement on Friday.

But the union said it was still considering whether to seek on its own a Supreme Court ruling that could limit Commissioner Roger Goodell's authority to punish players. Dropping the case now would leave in place a "broken system that must be fixed," the union said earlier this week.

Without a stay of the suspension, Brady would sit out the first four games of the season when the Patriots face the Cardinals, Dolphins, Texans and Bills. Backup Jimmy Garoppolo is expected to start for New England instead.

Brady would be eligible to return in Week 5, when New England is scheduled to visit the Cleveland Browns. Despite the suspension, the Patriots remain overwhelming favorites to win the AFC East for the 13th time in 14 seasons, and the gambling website Bovada listed them as the top choice to win the Super Bowl.

An NFL spokesman said the league would have no comment.

Originally suspended four games after the league concluded the Patriots intentionally underinflated the footballs used in the AFC Championship game on Jan. 18, 2015, Brady embarked on an odyssey to clear his name . A federal judge overturned the suspension, allowing Brady to play last season, but the 2nd Circuit reinstated it this spring.