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The Chicago Bears have pulled off a whopper of a trade the likes of which the team hasn't seen in nearly a decade.

The Bears will acquire All-Pro pass rusher Khalil Mack from the Oakland Raiders in a massive trade involving future picks. The Raiders have sent Mack and two 2020 draft picks (a second-rounder plus a conditional fifth-rounder) for the Bears' 2019 first-round pick, 2019 sixth-round pick and two picks in 2020 — their first- and third-round picks that year.

Mack and the Bears now have reached an agreement on a record-setting deal that will make him the highest-paid defender in the NFL — a six-year, $141 million extension (a $23.5 million per-year average) that includes $90 million guaranteed and $60 million at signing, per ESPN.

It's a deal that clearly signifies that the Bears are in go-for-it mode. Mack’s new contract eclipses the six-year, $135-million deal that DT Aaron Donald signed with the Rams on Friday. That contract includes $87 million in guarantees.

“We are excited to add a special playmaker like Khalil to our football team,” said Bears GM Ryan Pace in a statement issued by the team Saturday evening. “He brings a ton on the field, but he really fits what we are building in our locker room, too. Elite defensive players in their prime are rare so when we knew we had a legit shot to acquire him, we did everything we thought necessary to get him.

I’m confident the compensation to Oakland, including the return draft picks to us, and the contract extension for Khalil are fair to all parties. We are anxious to get Khalil to Chicago with his coaches and teammates.”

The Bears' biggest concern going into the season was edge rushing, and Mack almost instantly solves that. They're currently without OLB Leonard Floyd (broken hand), arguably their best pass rusher. He could be back for the season opener, but would have to play with his injured right hand casted and protected by a padded club. Now, the Bears can take pressure off Floyd by having an elite pressure player in Mack when they visit the Packers on Sept. 9, another team that reportedly was involved in the Mack Derby.

Mack will be an outside linebacker in defensive coordinator Vic Fangio’s defense, which ranked 10th last year in yards allowed and ninth in points. They were sixth in sack percentage, although Akiem Hicks, with 8.5, was their only player with more than 4.5 sacks.

Not since acquiring Jay Cutler almost a decade ago have the Bears made such a dramatic trade, but the Mack deal caps off a busy offseason in which the team rebuilt its offense around Mitch Trubisky and bolstered the defense with other moves.