FOXBOROUGH, Mass. -- 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 Brady's case was turned aside by the 2nd U.S. Circuit Court of Appeals. His 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.

Even if the union fights on, though, Brady would still 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.

Get Breaking News Delivered to Your Inbox

Patriots owner Robert Kraft, who has parted ways with longtime league allies over the punishment, renewed his complaint that the suspension was "unprecedented, unjust and unreasonable."

"Unfortunately, this stopped being about air pressure a long time ago," he said in a statement. "This entire process has indelibly taken a toll on our organization, our fans and most importantly, Tom Brady. His reluctant decision to stop pursuing further action and to put this situation behind him is what he feels is best for the team in preparation for this season and is fully supported by me and our entire organization."

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.

Along the way, prominent scientists have come to question the league's conclusions and legal scholars have doubted whether Goodell abused his power by punishing Brady a hefty four games merely for being "at least generally aware" of the deflation scheme. The appeals court panel found that the commissioner was acting with the wide-ranging authority granted to him by the collective bargaining agreement.

Kraft, who was instrumental in forging the labor deal that included the process upheld by the courts, took the nearly unprecedented step of opposing the league in court.

He again came to Brady's defense on Friday.

"What Tom has had to endure throughout this 18-month ordeal has been, in my opinion, as far removed from due process as you could ever expect in this country," he said. "From day one, I have believed in Tom and given him my unwavering support in his pursuit to rightfully clear his name of any wrongdoing."