BUFFALO – About 12 minutes into his third preseason outing, Sabres rookie Radim Mrtka saw an opportunity materialize deep in his own zone and took off down the middle of the ice.

When Mrtka, 18, reached the Detroit blue line, he caught up to forward Konsta Helenius, who held the puck on the left wing, and slipped past a Red Wings defender.

Helenius, 19, then pivoted and adroitly fed a streaking Mrtka, who beat Red Wings goalie Sebastian Cossa as he zoomed to the net.

“I saw the open ice, there was nobody, just Helly and one D,” the defense prospect told the Times Herald following Saturday’s 5-2 win in KeyBank Center. “So I saw an opportunity.”

Mrtka, the ninth overall pick this year, helped create that opportunity. For starters, coach Lindy Ruff, whose Sabres host a preseason game tonight against the Pittsburgh Penguins, said strong work in the defensive zone ignited the play.

“Then the ability to get up ice and beat his guy back up ice,” he said. “(It) was a great play, great pass. But great play to realize that he could be an outlet and he could be a threat, and skated right by his check. So heck of a goal for the young D-man.”

In his first weeks in Buffalo, the 6-foot-6, 218-pound Mrtka, the only junior player left among the 31 players in training camp, has impressed the Sabres with more than his talent.

First-round picks, of course, often receive long looks in camp. The Sabres, at least publicly, said before their preseason started they wanted to let Mrtka play a game.

Now, he has dressed for more contests than any defenseman on the roster. Yes, injuries have created openings in the lineup. Still, his play has warranted the action.

“I think earn is a pretty good word, and then coupled with a couple guys being out, we’ve been able to take a longer look at him,” Ruff said. “But when you see what he’s done since the start of prospect camp to where we’re at now, he’s got his game in a pretty good place.

“So I think it’s just trying to see where his game can be. Can he maintain, can he maintain a high-energy level through practices and games? And so far, he’s been able to handle it pretty well.”

So far, Mrtka has registered one goal and two points while averaging 18 minutes, 44 seconds of ice time per contest.

While it appears he will return to his junior team, the Western Hockey League’s Seattle Thunderbirds, before the NHL regular season starts, he might be ready to handle the rigors of pro hockey in the near future.

Ask Ruff or any of the Czech’s teammates what stands out about him, and you’re bound to hear about his maturity.

Remember, he arrived in North America about 10 months ago speaking little English while trying to adjust to a new culture and a different brand of hockey.

“So young but so mature,” Sabres captain Rasmus Dahlin said. “The way he plays it looks like he’s been playing here for a while. That big and can skate and can move, can score goals on the rush, you don’t find that very often. So I’m excited for his future.”

Mrtka displays his maturity in different ways.

As his goal illustrates, he thinks the game at a high level. Instead of an overwhelmed teenager, he often looks like an established pro.

“I know he’s young and it’s his first camp and everything, but, to me, he seems like he kind of brings that veteran presence,” said Sabres defenseman Jacob Bryson, who on Saturday played alongside Mrtka. “He’s very calm with the puck. He looks like he’s an experienced player. I thought he was really easy to play with.”

Ruff sees Mrtka’s maturity reflected in how he handles each practice.

“Just his practice habits are so good,” he said. “Like, he really practices hard. I think sometimes it can be difficult for a younger guy, his English is OK. For the most part, I think he understands.

“But I think stepping in at that age and adjusting to probably a different style of play, different system, I think he’s handled that all really good for a young player.”

– Make that three injured defensemen for the Sabres.

Ruff said Owen Power missed Tuesday’s practice with a strain and is day to day. He joins defensemen Bowen Byram and Mattias Samuelsson on the sideline.

Ruff said Byram, who suffered an undisclosed injury in Saturday’s game, skated on his own Tuesday. Samuelsson is week to week with an upper-body injury.

In other injury news, center Jiri Kulich, who tweaked a muscle Thursday, returned to practice Tuesday. Ruff said the Czech should be able to play tonight.

Meanwhile, Ruff said center Noah Ostlund, who was expected to begin the season with the Rochester Americans, is week to week with an undisclosed injury.

In lineup news, Ruff said goalie Ukko-Pekka Luukkonen, who missed the first week of camp with a lower-body injury, will be making his preseason debut tonight.

“Trying to decide whether play him the whole game or maybe just two periods,” Ruff said following Tuesday’s practice.

– Defenseman Zac Jones and forward Jake Leschyshyn both cleared waivers Tuesday and can report to the Amerks.