CHARLOTTE, N.C. -- Alex Guerrero, the personal trainer for New England Patriots quarterback Tom Brady, flew on the team plane in advance of Friday's preseason game against the Carolina Panthers, according to sources.

Guerrero's presence wouldn't have been as notable at this time last year, as he had been a regular on the team plane. But at some point during the 2017 season, Guerrero was no longer part of the Patriots' traveling party, which sparked questions as to whether there was tension between Brady and coach Bill Belichick.

While Guerrero wasn't traveling with the team, his access to Gillette Stadium to treat Brady was never restricted, per sources.

Last year, during the team's weeklong stay in Colorado Springs -- where the Patriots practiced in between games against the Denver Broncos and Oakland Raiders -- Guerrero stayed at the team hotel. In recent days, he has been a regular presence inside the locker room during the time in which reporters were present.

Guerrero, who is Brady's business partner at the TB12 Sports Therapy Center and was recognized by LaDainian Tomlinson in his Pro Football Hall of Fame induction speech for helping his career, also works closely with tight end Rob Gronkowski and wide receiver Julian Edelman, among other Patriots players.

NFL Network first reported that Guerrero flew on the team plane.