Rivera explained Newton, his starting quarterback for most of the previous nine years with the Carolina Panthers, has been trending toward full strength based on workout video he's watched.
"He's headed in the right direction," Rivera said on the McNeil & Parkins Show on 670 The Score in Chicago. "I mean, he's probably about as healthy as it gets from what I've seen on video. I think he's ready to bust out. I would never bet against the young man, that's for sure."
Newton missed the final two games of the 2018 season before undergoing offseason shoulder surgery. He returned for the start of the 2019 campaign but appeared in just two contests before suffering a foot injury that landed him on injured reserve.
The 31-year-old Atlanta native was having a strong year in 2018 with a 94.2 passer rating across 14 games before the shoulder injury. He was named the NFL's Most Valuable Player in 2015 after accounting for 45 total touchdowns (35 passing and 10 rushing). He also led Carolina to the Super Bowl that season.
Rivera said on the McNeil & Parkins Show he's bullish Newton will have a bounce-back year with the Pats:
"Don't bet against him. I really wouldn't. First of all, you got to know who he is and understand what all he's gone through. He's a guy that's always tried to do things, I think, because he's felt the pressure. He felt the pressure of being the No. 1 overall pick. He felt the pressure of having won the Heisman Trophy and being the No. 1 overall pick. He felt the pressure of being a black quarterback, with all the stuff that's been heaped on him.
"He's really had to find his way through it, and he's done a great job with it."
Newton is set to compete with Jarrett Stidham and Brian Hoyer to fill the massive void left by six-time Super Bowl champion Tom Brady in New England. Brady left in free agency to sign a two-year, $50 million contract with the Tampa Bay Buccaneers.
If healthy, the three-time Pro Bowl selection will be the heavy favorite to take over the starting job and, just when it looked like the other AFC East teams would finally enjoy a wide-open division race after two decades of Brady-led dominance, put the Patriots on the inside track toward the playoffs.
Newton and the Pats are scheduled to open the preseason Aug. 13 against the Detroit Lions.