BOSTON (CBS) — While Rob Gronkowski’s injury is not considered to be serious, it appears the Patriots are taking a very cautious approach with the All Pro tight end.

After leaving New England’s first joint practice with the Chicago Bears with a “minor” injury on Monday, Gronkowski was not spotted on the practice field to start Tuesday’s session.

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In addition to Gronkowski, running back Brandon Bolden was also a new addition to the Patriots’ absentee list on Tuesday. Running back Dion Lewis, linebacker Shea McClellin, offensive linemen Jonathan Cooper and Sebastian Vollmer and defensive lineman Jabaal Sheard were once again missing from practice on Tuesday.

There were a few faces back on the field, though not in pads: Wide receiver Danny Amendola, special teamer Nate Ebner and offensive lineman Tre’ Jackson.

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Ebner is back after his run with the U.S.A rugby team in the Rio Olympics.

Defensive lineman Rob Nickovich was back on the field in full pads on Tuesday, just one week after he suffered a triceps injury that was expected to sideline him for 4-6 weeks. Ninkovich first returned to the practice field on Sunday, and donned the pads for the first time on Monday.

Rookie receiver Malcolm Mitchell, who suffered a nasty arm injury last Thursday in New England’s preseason opener against the Saints, was also back on the field Tuesday with a giant brace on his arm.

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Tune in to Thursday night’s Patriots-Bears preseason game on 98.5 The Sports Hub and WBZ-TV — the flagship stations of the New England Patriots! Kickoff is set for 8pm, with pregame coverage beginning on The Sports Hub at 5pm and Patriots All Access on WBZ-TV at 7:30pm!