FOXBORO — The Patriots have spent nearly two weeks operating under the assumption they would have their star trio of pass-catchers on the field Saturday for the first time in two months.

But there was a wrench thrown in the way yesterday. Tight end Rob Gronkowski was the only one missing from practice.

It’s unclear why Gronk wasn’t present for the session, which was held in full pads at Gillette Stadium. The Patriots won’t release an injury report until today, so there hasn’t been an official word on his absence.

Gronkowski’s knee hasn’t been on an injury report since Week 14, and he was present for both walkthroughs last week and Monday’s week-opening workout.

It was the seventh time Gronkowski missed practice since the start of the season. He was held out of four workouts in Weeks 13-14 because of a sprained and bruised knee and missed two more workouts last month after the death of a close friend.

Gronkowski’s absence could have been for any number of reasons, including rest, personal or a seasonal illness, and the alarms can be silenced if he returns today.

In other practice news, safety Nate Ebner returned to practice after missing Monday’s workout. Ebner has been wearing a hard cast on his right hand, wrist and forearm since last week.

Malcom in middle

Rookie defensive tackle Malcom Brown has become a staple up front and is gearing up for his playoff debut against the Chiefs.

“Everybody will be playing harder than they played during the (regular) season, so you just go out there and expect everybody’s best,” Brown said.

Brown has really had it going since the Patriots’ victory against the Cowboys in Week 5 and has become more consistent with each passing month. He had three sacks, one quarterback hit, six pressures, two fumble recoveries, three drawn holding penalties and seven run stuffs during the regular season.

The first-round pick didn’t think anything really clicked at any point, and he credited the surge to a steady progression.

“Just preparation,” Brown said. “Just go out there and continue practicing, getting better at what I can and what they want me to do.”

Brown never played more than 13 games in a collegiate season at Texas, so there’s always a concern about the rookie wall. Brown is getting ready to strap on the helmet for the 21st time in Saturday’s divisional playoff, including four preseason games.

He shrugged off the notion of fatigue.

“I feel good,” Brown said. “I don’t feel any different than Game 1, so I’ve just got to keep on getting better.”

Brown has been said to be well-conditioned, and he has followed the Patriots’ strict workout plan to remain at the mandated 319 pounds throughout the season. That definitely plays a factor in his ability to stay as fresh as possible at this juncture.

“It’s really just the love of the game,” Brown said. “When you really love something, it really doesn’t take a toll on me like, ‘Oh man, I don’t really want to go out there and do this today.’ When you really love the game, it’s just like, ‘Oh, I get to wake up and do this again, something that I love.’ ”

Despite the excitement of his impending playoff debut against the streaking Chiefs, Brown stressed it’s been important to stay even-keeled during the two-week buildup. Brown’s mental focus has not changed for months.

“Definitely just want to continue to get better, think about what I’ve been doing bad, my weaknesses, and trying to get those better,” he said.

Black-eyed BB

The Patriots’ injury bug has caught up to the coaching staff.

Bill Belichick had a black eye yesterday but shook it off when pressed for his condition.

“I think I’ll live,” Belichick said.

As for tomorrow’s injury report?

“I don’t think we have to list the coaches on the injury report,” Belichick said. “But I’m sure if we’re required to do it, we’ll do it.”