Matt Asiata, the Vikings running back who rushed for 91 yards on 19 carries in the season-ending 13-9 victory over the Chicago Bears on Sunday, believes he has shown the ability to replace Adrian Peterson as the starting running back if Peterson doesn't return.

"Think I can do it? Yes. No doubt in my mind," Asiata said, adding: "The more experience I got, the better it is for the future. It is what it is. See what the coaches like, and we'll move forward."

The 91 yards were his most rushing since he ran for 115 yards in last year's season finale, a 14-13 victory over the Detroit Lions in the final game at the Metrodome.

"I was just trying to get first downs and move the ball for our offense and execute," Asiata said. "Our offensive line did a great job and Jerome Felton and Joe Banyard did a great job."

Said coach Mike Zimmer: "I thought Matt ran great today. He ran with a purpose — strong, good cutbacks. He came up to me to me after that fourth-and-1 [after he failed to get a first down late in the game] and said, 'I messed that up. I should have got it.' "

Asiata has averaged only 3.5 yards per carry both this season (164 carries, 570 yards) and in his career (211 carries, 745 yards). But he has shown improvement, and if he can perform every game like he did Sunday he might not be kidding.

Asiata went undrafted out of Utah, signing with the Vikings as a free agent in 2011 but failing to make the team. But the Vikings brought him back the following year and he made the team out of training camp as their No. 3 running back, beating out Jordan Todman. But he had only three carries in 2012 and didn't have any last year until Week 15 against Philadelphia. That was when Asiata, filling in for the injured Peterson and Toby Gerhart, rushed for three touchdowns in his first career start, the first NFL player to do so since quarterback Daunte Culpepper did it for the Vikings in September 2000.

This season, Asiata has had two more three-touchdown games, against Atlanta on Sept. 28 and Washington on Nov. 2. He's the only undrafted player to have three three-TD games in his first three seasons since 1967.

Even though it's assumed Peterson will be reinstated from his suspension, there's a chance his career with the Vikings will be over if he refuses to renegotiate the $13 million salary he is due in 2015. If that's the case, the starting running back job will be wide open.

But even if Peterson returns, Asiata believes he has earned a position as a backup based on his improved performance this year in Peterson's absence.

"The thing that Asiata does, he runs with his pads over his shoulders and he's got great feet and he is a good kid," Zimmer said. "He's really a good kid."

Sleeper makes it big

Adam Thielen, who didn't gain a lot of recognition as a football player at Detroit Lakes and at Minnesota State Mankato, scored his second touchdown of the season and first as a receiver when he caught a deep pass in stride from Teddy Bridgewater and ran in for a 44-yard score. That came one play after Thielen caught a 22-yard pass on third-and-9.

"I think they dropped the coverage," Thielen said. "I think they had one guy playing Cover 2 and the rest were playing man. I inside-released and Teddy found me."

Said Zimmer: "It's great, a guy like him, he goes out and busts his rear end each and every week. He does whatever he can do for him to get the opportunity and they busted the coverage."

Credit goes to Rick Spielman and his scouting staff for finding a real sleeper as a free agent. Like Asiata, Thielen has shown how undrafted players can still make it big. He scored his first career touchdown Nov. 30 against Carolina when he blocked a punt and returned it 30 yards for a score.

Thielen, who was invited to a rookie tryout camp last year before eventually spending 2013 on the Vikings practice squad, had five receptions for 69 yards this year going into Sunday, when he caught three passes for 68 yards.

In addition, he made a big play on special teams in the fourth quarter. After Blair Walsh's 44-yard field goal gave the Vikings a 13-6 lead, Bears return man Marc Mariani returned a kickoff 67 yards, but Thielen was able to catch him from behind and bring him down at the Vikings 35-yard line. Chicago managed only a field goal from there.

Thielen said he didn't think about his career in terms of taking advantage of his opportunities, adding, "I just want to go out and do my job and what the coaches ask me to do to help this team win."

Thielen credited wide receivers coach George Stewart and assistant receivers coach Klint Kubiak for his development. "It's pretty awesome to have coaches like we've had," Thielen said. "… I've gotten a lot better and it's a testament to them and also to the veterans in our receivers room. We all help each other out. I feel like I've got a long ways to go, and I've gone a long ways too because of those guys.

"You know, it was just good coaching. They put me in the right position. And I didn't really have to do much. Makes it easy when you can have catches like that and you don't have to do much."

Incidentally, following his touchdown catch, Thielen threw the ball in the area where his fiancée was sitting, and she caught the ball.

Didn't have play in

One of the big surprises in Sunday's game was that Audie Cole, substituting for the injured Chad Greenway, led the Vikings in tackles with 14.

Zimmer praised Cole for his performance, noting the fact that Cole was playing out of position. No doubt it was a game that won't hurt Cole — a seventh-round pick in 2012 — in the plans for the team going forward.

Trestman deserving

Following the game, Marc Trestman, the St. Louis Park High School product and former Gophers quarterback in his second year as Bears coach, said he expects to be back in 2015 despite Chicago's 5-11 record.

I agree with him. Maybe I'm prejudiced because I know what a football brain he is.

"I don't have to go into reasons, I expect to be back," said Trestman, who has had to endure injuries along with having ineffective Jay Cutler at quarterback. "I couldn't look at it any other way or with any other kind of focus."

If Trestman, who went 8-8 last year, is fired, it's hard to imagine the next coach having any more success, given the problems on the Bears roster.

When you decide to bench your $126 million quarterback, you know it's not the coach.

Sid Hartman can be heard weekdays on 830-AM at 7:40, 8:40 and 9:20 a.m. and on Sundays at 9:30 a.m. shartman@startribune.com