(CNN) Tom Brady , the six-time Super Bowl winner who is widely regarded as the greatest NFL quarterback in history, has said he will not be re-signing with the New England Patriots, ending one of the most successful partnerships in sports.

The 42-year-old has spent his entire 20-year NFL career with the Patriots, leading the franchise to nine Super Bowls with Brady as quarterback and Bill Belichick as head coach.

"I don't know what my football future holds but it is time for me to open a new stage," Brady posted on his social media accounts, in a statement entitled "Forever a Patriot."

Brady is expected to agree to terms with the Tampa Bay Buccaneers, according to reports from NFL Network's Ian Rapoport and ESPN's Adam Schefter.

Neither the Tampa Bay Buccaneers nor Tom Brady's representation have responded to CNN's request for comment.

Brady, who turns 43 this summer, will become an unrestricted free agent when free agency opens Wednesday at 4 p.m. ET.

Photos: NFL legend Tom Brady Quarterback Tom Brady was with the New England Patriots for two decades, winning a record six Super Bowl titles. He is now a Tampa Bay Buccaneer. Hide Caption 1 of 25 Photos: NFL legend Tom Brady Brady played college football at the University of Michigan. He started for the Wolverines in his junior and senior seasons, going 20-5. Hide Caption 2 of 25 Photos: NFL legend Tom Brady Brady grew up in San Mateo, California, and played football, basketball and baseball before joining Michigan. Hide Caption 3 of 25 Photos: NFL legend Tom Brady Despite his successful career at Michigan, Brady was not projected to be a star in the NFL. He was the 199th player taken in the NFL Draft. Many quarterbacks were taken before him. Hide Caption 4 of 25 Photos: NFL legend Tom Brady Brady started his career backing up Drew Bledsoe. But when Bledsoe was hurt in September 2001, Brady got his chance to shine. He took over as starter and led the Patriots all the way to the Super Bowl. Hide Caption 5 of 25 Photos: NFL legend Tom Brady Brady loses the ball after being hit by Oakland's Charles Woodson during an NFL playoff game in January 2002. The Patriots got the ball back and went on to win the game, but the controversial play was heavily debated in the offseason. The "tuck rule" was eventually repealed in 2013. Hide Caption 6 of 25 Photos: NFL legend Tom Brady The 2001 season culminated in a Super Bowl victory for Brady and the Patriots in February 2002. They upset the heavily favored St. Louis Rams 20-17. Brady was named Super Bowl MVP, and he became the youngest quarterback to win a Super Bowl. He was 24. Hide Caption 7 of 25 Photos: NFL legend Tom Brady Brady and the Patriots were back in the Super Bowl in 2004, winning another title over the Carolina Panthers. They repeated the next season with a Super Bowl win over Philadelphia. Hide Caption 8 of 25 Photos: NFL legend Tom Brady Brady and Patriots coach Bill Belichick celebrate after a playoff win in January 2007. The two were together for Brady's entire Patriots career. Hide Caption 9 of 25 Photos: NFL legend Tom Brady Brady throws a pass during a game in Cincinnati in October 2007. Hide Caption 10 of 25 Photos: NFL legend Tom Brady Brady is surrounded by the media in 2007. The Patriots went undefeated in the regular season but lost to the New York Giants in the Super Bowl. Hide Caption 11 of 25 Photos: NFL legend Tom Brady New York Giants defensive end Justin Tuck strips the ball from Brady during the Super Bowl in February 2008. Hide Caption 12 of 25 Photos: NFL legend Tom Brady Brady leaves the field in 2012 after another Super Bowl loss to the Giants. Hide Caption 13 of 25 Photos: NFL legend Tom Brady Brady kisses his mother, Galynn, after the Patriots defeated Seattle for their fourth Super Bowl title in February 2015. Hide Caption 14 of 25 Photos: NFL legend Tom Brady An opposing fan taunts Brady as he takes the field in August 2015. Brady was eventually suspended four games over the "Deflategate" controversy, which involved allegations that the Patriots purposely deflated balls to gain an advantage on offense in an AFC Championship game. Hide Caption 15 of 25 Photos: NFL legend Tom Brady Brady drops back to pass during a game against Dallas in October 2015. Hide Caption 16 of 25 Photos: NFL legend Tom Brady Brady arrives at a federal court to appeal his suspension for "Deflategate." Hide Caption 17 of 25 Photos: NFL legend Tom Brady Brady is tackled by Denver's Aqib Talib in the AFC Championship game in January 2016. Hide Caption 18 of 25 Photos: NFL legend Tom Brady Brady raises the Vince Lombardi Trophy after leading the Patriots to their fifth Super Bowl victory in 2017. The Patriots were trailing 28-3 before pulling off the biggest Super Bowl comeback ever and winning in overtime. Hide Caption 19 of 25 Photos: NFL legend Tom Brady Teammate Rob Gronkowski playfully steals Brady's jersey before a Boston Red Sox baseball game in April 2017. Brady had just had his Super Bowl jersey returned by authorities after it had been stolen from the locker room. Hide Caption 20 of 25 Photos: NFL legend Tom Brady Brady and his wife, model Gisele Bundchen, attend the Met Gala in New York in 2018. Hide Caption 21 of 25 Photos: NFL legend Tom Brady Brady throws a football in Monaco during a promotional event for watchmaker TAG Heuer in 2018. Hide Caption 22 of 25 Photos: NFL legend Tom Brady Brady celebrates after an overtime win in January 2019 that put that Patriots in the Super Bowl. Hide Caption 23 of 25 Photos: NFL legend Tom Brady Brady celebrates with his daughter, Vivian, after winning his sixth Super Bowl in 2019. Hide Caption 24 of 25 Photos: NFL legend Tom Brady Brady's last game with the Patriots was a playoff loss to Tennessee in January. Hide Caption 25 of 25

Unprecedented success

During his two decades with the Patriots, Brady was coached by the edgy Belichick and together the pair brought unprecedented levels of success to the team. Belichick described him as "not just a player who bought into our program."

LOVE YOU PATS NATION pic.twitter.com/lxSQZmnjPL — Tom Brady (@TomBrady) March 17, 2020

"He was one of its original creators," the head coach told the Patriots' website. "Tom lived and perpetuated our culture.

"On a daily basis, he was a tone setter and a bar raiser. He didn't just perform. He didn't just win. He won championships over and over again.

"Sometimes in life, it takes some time to pass before truly appreciating something or someone but that has not been the case with Tom. He is a special person and the greatest quarterback of all-time."

The 199th pick in the sixth round of the 2000 draft, Brady rose from relative anonymity to become an NFL great.

He has won three NFL Most Valuable Player awards and leaves the Patriots second in the NFL all-time list in passing touchdowns (541) and passing yards (74,571).

Since getting his first chance in 2001, courtesy of an injury to then starter Drew Bledsoe, Brady has gone on to break numerous records, including most Super Bowl victories by a player (six), most Super Bowl MVPs (four) and most regular-season wins by a starting quarterback (219).

In the 2019 season, Brady led the team to the first round of the playoffs with a 12-4 record, and suffered a upset home loss to the Tennessee Titans.

Addressing teammates, coaching staff and Patriots executives, Brady said in Tuesday's statement: "You all have allowed me to maximize my potential and that is all a player can hope for.

"Everything we have accomplished brings me great joy and the lessons I have learned will carry on with me forever.

"I couldn't be the man I am today without the relationships you have allowed me to build with you."

Brady pictured after the Patriots' 20-13 loss to the Tennessee Titans.

Brady, who will be on the open market for the first time in his long career, did not indicate which team he will sign with for the 2020 season.

"I love Tom like a son and I always will," Patriots owner Robert Kraft said

"He has brought so much happiness to me personally and to all of our fans. I had hoped this day would never come, but rather that Tom would end his remarkable career in a Patriots uniform after yet another Super Bowl championship."

The Buccaneers, with 2013 Heisman Trophy winner Jameis Winston as quarterback, went 7-9 last season. They didn't advance to the NFL playoffs.