GREEN BAY — Jared Cook has watched impatiently from the sideline for the last five weeks, anxiously waiting to reassume his place in the Packers’ offense.

It’s unfamiliar territory for the veteran tight end to sit, considering he played in 107 of a possible 112 regular-season games prior to signing with the Packers in March.

 The ankle injury Cook suffered in Week 3 against Detroit is the first real setback he’s encountered during his eight NFL seasons.

“It’s tough because it’s my first time actually going through it,” said Cook on Thursday. “A lot of things that I had to get used to and a lot of things I had to do differently.

“It’s really tough. It’s hard. It’s really hard, especially sitting on the sideline watching games when you know you could be out there helping your friends and your teammates. It’s difficult. It’s really hard.”

The 6-5, 254-pound tight end was gaining his footing in the offense when he left in the second quarter of an eventual 34-27 win over the Lions at Lambeau Field on Sept. 25.

He and injured running back James Starks (knee) both returned to practice last Thursday in limited fashion before ramping up their workload this week.

While neither player is making any predictions about his availability for Sunday’s game against Tennessee, Cook has plenty of motivation to get back on the field.

The Titans drafted Cook out of South Carolina in the third round in 2009. He played his first four seasons in Tennessee, catching 131 passes for 1,717 yards and eight touchdowns.

Cook also met his wife, Lana, during his time in Nashville and still has many close friends in the area.

“Of course it would,” said Cook when asked if it would be special to play against Tennessee. “It was kind of the kick-start of my career, so it would be awesome. But you also have to be smart with the decisions that you make from here on out.”

The offense has changed since Cook was last on the field. With mounting injuries at several skill positions, Head Coach Mike McCarthy has incorporated more packages to better utilize the offense’s available personnel.

McCarthy said on Thursday morning that he and the coaching staff currently have 21 personnel packages in this week’s game plan, which is the most he can remember.

Comparatively, McCarthy said the Packers typically had six-to-10 packages in the game plan when they were operating mainly out of their up-tempo, no-huddle offense.

One reasons for the increased complexity is due to the uncertainty regarding the availability of Cook and Starks, who’s missed the last four games since undergoing knee surgery.

With Starks injured and Eddie Lacy on injured reserve, the Packers have turned to practice-squad running back Don Jackson and second-year receiver Ty Montgomery in the backfield.

Montgomery has blossomed in his new role the past month with all of his production (23 catches for 202 yards and 21 carries for 119 yards) coming in only three games.

“I think Don and Ty and those guys did a great job of doing everything they have to do,” Starks said. “I can come and try to add onto what they’re doing and we can continue to try to be successful and try to help the team.”

During the recent switch-up – an alteration McCarthy said the offense will stick with going forward – the Packers have utilized more four- and five-receiver packages.

It’s helped get the passing game into rhythm, but also resulted in more defensive coordinators recently countering with man-to-man coverage.

Those are opportunities receivers and tight ends relish, and a prospect that has Cook salivating once he’s back on the field.

“I think it should open things up a little bit more,” Cook said. “Teams have been playing us a lot in man the past three games. Those are the fun games you want to play in. I’m looking forward to getting back and being around the fellas. I miss them. I hope they miss me, too. I just want to get out there and help as much as I can.”

It remains to be seen whether Cook or Starks will be back in time for Sunday’s game. Cook said he was a week off the timeline he was given for his recovery, while Starks lists himself as “day-to-day.”

Whenever the two return, it should go a long way in helping expand the big-play opportunities for an offense that’s continuously innovated to stem the tide until their return.

“You see the different things that Coach McCarthy is doing,” Cook said. “It is exciting, but just imagine if you were able to do more two-tight-end sets or three-tight-end sets or if you had James back and you had Ty. There’s a lot of factors that could be involved in this offense getting better.”