PITTSBURGH – Zack Mitchell took the long, hard route to his eventual NHL debut for the Wild in Thursday's 4-2 win over the Pittsburgh Penguins.

Undrafted, Mitchell spent five years playing for the Ontario Hockey League's Guelph Storm, then signed with the Wild and spent two full seasons in Iowa without even a call-up before Wednesday's surprise promotion.

"I'm proud of the fact that I'm undrafted. I wouldn't change it if I could," said Mitchell, 23. "It's not the easiest route, that's for sure. At the same time it's helped me build character that maybe I wouldn't have built if I was drafted."

Mitchell, whose father, Tim Mitchell, attended Thursday's game, was a goal scorer in juniors, topping 30 twice and 22 another season. His final year in 2013-14, Mitchell scored 83 points and led the Storm to a championship with 12 goals and 30 points in the playoffs. Those numbers ranked third and second in the OHL.

Mitchell led Iowa with 22 goals and 42 points last season but had only a goal and no assists in 11 games this season. He injured an ankle training this summer and missed all of camp, so coach Bruce Boudreau said the first half-dozen Iowa games were like his training camp.

"[Iowa coach] Derek Lalonde was really patient with me," Mitchell said. "He did a great job giving me some time so I was able to get back into game shape. The last couple weeks I've been starting to feel like myself."

Boudreau tried to put him in a position to succeed by having him play the right side with Jason Zucker and Erik Haula, who returned from a foot injury and played for the first time since Oct. 20.

Haula was injured blocking a slap pass on a delayed penalty in the home opener, but he played two more games until "I could hardly walk." His return came after only one practice, so conditioning could be an early issue.

"I guess time will tell," Haula said.

Boudreau loved his game Thursday, saying Haula "gave me another option" on the penalty kill and coming back with him after power plays.

Bertschy, Prosser out

With Haula back and Mitchell's debut, Christoph Bertschy was scratched. But Chris Stewart could be close to seeing the press box. He entered Thursday's contest with two goals, three assists, four shots and five hits in 11 games.

"Not enough. We need something out of him," Boudreau said. "He's had parts of really good things, but those numbers indicate right there for a guy of his stature, he should be having more. That means he should be going to the net more, that means he should be more physical, all of those things."

Stewart had five more hits Thursday.

With defenseman Mike Reilly back up, Nate Prosser was scratched.

Trying to repeat

After his buddy Eric Staal signed with the Wild on July 1, Matt Cullen thought his return to the Wild would follow so he could maybe end his career "at home."

It never transpired, so the 40-year-old returned to the Penguins, where he has gotten to take part in the Stanley Cup champion ring ceremony, banner raising and White House salute.

"It was an interesting summer, I'll say that," Cullen said. "[The Wild] was definitely a possibility and on the radar, but it's nice being back here. It's comfortable and a great setup for my family. Also, I've really enjoyed being the reigning champs because everybody gives you their best game and there's all this excitement around every game. It's a new challenge. I've never experienced trying to [repeat]."

Cullen won a Stanley Cup with Carolina in 2006, but he signed with the Rangers that offseason.