Unclear how long the duo worked out together ... but check out the vid of the two afterward -- Sanu is ripped, and Newton is still big as hell!!
Of course, Newton and Sanu have a relationship dating back YEARS ... they were rivals during their times in Carolina and Atlanta -- and they had already been spotted working out together earlier this year before Cam signed with Bill Belichick's squad.
But, it's clear the workouts mean more now ... Cam's expected to be the starter in New England, while a finally-healthy Sanu is slated to be the team's No. 2 WR target behind Julian Edelman.
By the way, this also helps explain why Cam touched down in Los Angeles rather than New England earlier this week after signing his contract ... gotta build that rapport early!!