FOXBORO, Mass. — Rob Gronkowski has known only one starting quarterback during his New England Patriots career. But if Roger Goodell and the NFL have their way, that will change this season.

With Tom Brady currently fighting a suspension that would keep him out until Week 5, the Patriots are preparing to begin the regular season with Jimmy Garoppolo as their No. 1 QB.

Whether Garoppolo will be ready for the challenge is anyone’s guess at this point. The 2014 second-round draft pick attempted just 31 passes over his first two seasons and has yet to start an NFL game.

Garoppolo has impressed so far this offseason, however, and Gronkowski believes the 24-year-old’s grasp of New England’s complicated offense has improved by leaps and bounds.

“He’s doing great, definitely,” Gronkowski said Monday after the Patriots completed their final open day of organized team activities. “You can see a huge development over the last two years in the way he handles the offense now. He’s doing a great job going out there, listening to coaches and just working together with the whole team.”

Garoppolo completed six of his 10 passes during Monday’s workout, which featured far less full-speed work than previous OTA/minicamp sessions that were open to the media. Over the five unpadded practices reporters were allowed to attend this offseason, he completed 76.1 percent of his throws (118 of 155) and was picked off three times.

His best two showings came on the first open day of OTAs and the opening day of minicamp, during which he combined to go 59 of 72 (81.9 percent) and — far more importantly — looked much more comfortable than he did during his first two NFL offseasons.

Gronkowski, meanwhile, practiced in front of the media for the first time Monday after sitting out the previous four sessions.

Thumbnail photo via Winslow Townson/USA TODAY Sports Images