The Vikings defense has shown steady improvement in four seasons under head coach Mike Zimmer and defensive coordinator George Edwards.

In Zimmer’s first season as head coach, 2014, the Vikings defense ranked 11th in the NFL in fewest points allowed and 14th in fewest yards allowed.

In 2015, the Vikings improved to fifth in points allowed and 13th in yards allowed. Before 2015, the last time the Vikings ranked in the top 10 in fewest points allowed was 1998.

Last season the Vikings were sixth in points allowed and third in yards allowed.

Going into Sunday’s game against the Bears, the Vikings defense ranked first in the NFL this season in fewest points allowed and fewest yards allowed. In their 23-10 victory over the Bears, the Vikings held Chicago to 201 yards and 12 first downs and no offensive touchdowns. The Vikings held the Bears to 30 yards rushing — minus-1 yard in the first half.

The Vikings limited Bears running back Jordan Howard to 9 yards in nine carries. Howard entered the game fifth in the NFL with 1,113 yards rushing. In the first meeting between the teams this season — in Week 5 on Oct. 9 — Howard rushed for 76 yards in 19 carries. In that game, a 20-17 victory by the Vikings that started an eight-game winning streak, the Bears rushed for 115 yards and 274 yards in total offense.

“It was a good team win today,” Zimmer said. “I thought we played exceptionally on defense, the two goal-line stands.”

Both of the goal-line stands came in the fourth quarter. On the first, the Bears drove to a first-and-goal at the Vikings 6-yard line. But the Vikings stopped the Bears on four incomplete passes to maintain a 23-7 lead.

Trailing 23-10, the Bears took over at their own 36 with 5:34 remaining and drove to the Vikings 2-yard line. Four plays — three runs and a pass — netted 1 yard. Linval Joseph and Everson Griffen stopped Bears receiver Tarik Cohen at the 1 on fourth down. Late in the first half Joseph had hurried Bears QB Mitchell Trubisky into an intentional-grounding penalty in the end zone that resulted in two points (and a 16-7 lead) for the Vikings.

“I like how this defense plays,” Zimmer said. “They’ve got a little chip on their shoulder. They play hard and physical and they play well together. Defensively, any time you can be No. 1 in the league in scoring defense and third downs, you’re doing something right.”

The last time the Vikings ranked first in both fewest points allowed and fewest yards allowed in the same season was 1970, and they also did it in 1969. In 1971, the Vikings allowed the fewest points and were second in fewest yards allowed.

Thirteen victories

The Vikings’ 13 regular-season victories are the second most in franchise history.

“Thirteen wins is hard to get,” Zimmer said. “They battled all year long. They’ve been in a lot of crunch situations. They figured out how to win games, and I think we have a good team. I like this team.”

This is just the third time since the NFL went to a 16-game schedule in 1978 that the Vikings have won at least 12 games. The Vikings have won 12 games five times, most recently in 2009.

Only their 15-1 mark in the 1998 season is better than this year’s 13-3 mark.

Zimmer credits the players and front office for the successful season.

“We’ve continued to add depth,” Zimmer said, then praised Executive Vice President Rob Brzezinski, assistant General Manager George Paton and General Manager Rick Spielman. “I can’t say enough about our front office guys. The guys we’ve added in the draft. The guys we’ve added in free agency. A lot of guys have come up and played well.”

Zimmer said he has been pleasantly surprised.

“The improvement in the offensive line has been huge,” he said. “Case Keenum. Trae Waynes. Andrew Sendejo has played outstanding. You know, you could go on and on and on about a lot of these guys. Eric Kendricks has had a great year. [Anthony] Barr has played well. Guys keep stepping up and making plays, and that’s what you need to do if you’re going to win 13 games.”

Things to work on

The Vikings got off to a good start on Sunday, putting together drives of 70 and 71 yards en route to a 14-0 lead with 9:30 remaining in the first half.

“Offensively we started fast,” Zimmer said, “and then we ended up messing up a little bit, getting some penalties. So those are some things we can clean up.

“Obviously today, we had too many penalties. Some holding calls that set us back. We can’t do that. We’ve got to take advantage of field position that we had today. I’m going to sit down and really evaluate some of these things tonight and tomorrow.”

The Vikings ended up with 12 penalties for 103 yards and converted just two of six third-down situations in the second half. For the game, the Vikings were 5-for-13 on third down.

Murray strong

There were some offensive highlights for the Vikings on Sunday.

Latavius Murray rushed 20 times for 111 yards (5.6 per carry) and scored two touchdowns. Going into the game, Murray had rushed for 731 yards and was averaging 3.7 yards per carry.

“He had a good year, and he’s come on strong at the end of the year. And that’s important,” Zimmer said. “I thought he found some creases. Their team is a good defensive team. They don’t give up many big plays. I think our offensive line did a good job. It was rebuilt for this game and did a nice job getting these guys moved so we could get some yards, and Latavius took advantage of it.”

Efficient passing

Keenum completed 21 of 29 passes for 189 yards and a TD and a 101.1. quarterback rating.

Stefon Diggs and Adam Thielen each caught six passes.

“They’re both good guys. Good workers,” Zimmer said. “[Offensive coordinator] Pat [Shurmur] does a nice job with schemes so they can get open, and then they make nice plays.”

Line does good job

The Vikings used their seventh different combination of offensive lineman Sunday. The revamped line with Joe Berger at center allowed just two sacks and, led by Murray, the Vikings rushed for 147 yards and averaged 4.1 yards per carry.

“They [the Bears] had a big physical front,” Zimmer said. “Our offensive line had some new pieces in there. They did a good job.”

Another player who made a big contribution Sunday was backup tight end David Morgan. Morgan, who had just seven receptions going into the game, caught three passes for 35 yards.

“Three big ones, too,” Zimmer said. “On second-and-25 he caught one to get it to third-and-8, then he caught another for a first down, and that was huge.”