ALLEN PARK -- Louis Delmas barely touched the field during training camp, casting doubt over the health of his chronically painful left knee.

Four weeks later, he's silenced all doubts with authority.

The Detroit Lions safety has played all but two snaps through the first month of the season, and is blooming alongside new batterymate Glover Quin.

Detroit Lions safety Louis Delmas, shown celebrating an interception against the Bears, is off to one of the best starts of his career.

Delmas is rated by Pro Football Focus as the fifth-best safety in the NFL, while Quin is 23rd. They are the highest-ranked safeties in the NFC North.

"It's a simple mind-set now, to know that I'm back there with a guy who not only plays for himself but he plays for his teammates," Delmas said. "He'll risk his body and risk his job to put a teammate in a great position. I'm proud to be playing next to him."

Those guys were terrific Sunday in a 40-32 win against the Chicago Bears (3-1). Delmas picked off quarterback Jay Cutler twice, Quin added one of his own and they combined for five passes defended.

The only other Detroit player ever to pick off Cutler was Aaron Berry in 2010.

Delmas' breakthrough gives him some impressive numbers through four weeks of the season. Quarterbacks are just 1-of-6 passing for minus-3 yards and two interceptions when they throw his way.

That's a 0.0 passer rating, the best in the NFL among safeties who have played at least half their team's defensive snaps.

Delmas ranks as the No. 1 cover safety in football. His run support is just 40th, although coach Jim Schwartz sure isn't concerned about his tackling.

"That's one of the things that's one of Lou's best assets, is his ability to make open-field tackles and things like that," Schwartz said. "I think that comes from just being on the field more and things like that. He didn't have a whole lot of practice time last week, but his game experience has increased this year."