Chicago (CBS) — Chicago Bears outside linebacker Khalil Mack has been named the National Football Conference Defensive Player of the Month for September.

Mack is ranked second in the NFL with five sacks and is number one with four forced fumbles. He recorded a strip/sack in each of the Bears’ first four games, becoming the first NFL player to do this since the Colts’ Robert Mathis in 2005.

The Bears have won three of their first four games this season and are currently in first place in the NFC North.

The Bears acquired Mack September 1 in a trade with the Oakland Raiders.

Bears defensive coordinator Vic Fangio spoke highly of Mack’s performance and work ethic.

“I think what I’ve enjoyed most about him is the guy does not have an ounce of prima donna in his body,” Fangio said. “He’s a joy to be around. The other players like being around him. The coaches like being around him. Besides his talent and production, which everybody sees, he’s really a breath of fresh air to be around, too, on a daily basis.”

Mack is the first Bears player to win an NFC player of the month award since cornerback Charles Tillman in October 2012.