If Ivan Barbashev felt any anxiety Wednesday, he didn't show it. Hours before his NHL playoff debut, the St. Louis rookie center cheerily answered questions about facing the Wild, with a giddy grin that never left his face.

Barbashev, 21, began the series in a rather surprising place: on the Blues' top line, between wingers Vladimir Tarasenko and Jaden Schwartz. The happy anticipation he displayed Wednesday helped explain coach Mike Yeo's choice to place someone so green in such a prominent position. In his first three months on an NHL roster, Barbashev has been both fearless and opportunistic, earning the trust of his coach and teammates.

The playoff opener brought the young Russian back to Xcel Energy Center, where he made his NHL debut last Jan. 26. In his first NHL playoff game, he saw 18 minutes, 36 seconds of ice time, delivered two hits and was on the ice when Joel Edmundson scored the winning goal in a 2-1 Blues victory.

"Since last year, when I played in the [AHL], my game has been growing and growing,'' said Barbashev, who finished his first NHL regular season with five goals and seven assists in 30 games. "It's just getting better, especially in the defensive zone. I've been working a lot.''

That has endeared him to Yeo, who took over as the Blues' head coach shortly after Barbashev's promotion from the team's AHL affiliate in Chicago. For much of his early run with St. Louis, Barbashev labored on the third or fourth line.

His steady improvement led Yeo to elevate him to the top line for the final three games of the regular season. In a more prominent role with greater ice time, Barbashev has flourished, and he entered the playoffs on a four-game point streak.

"[Barbashev] is a guy that's a complement to [Tarasenko and Schwartz],'' Yeo said. "He can create. He can make plays. He hasn't shrunk in the moment and with the opportunity to play with top guys, like many young players would.

"If anything, he's risen to the occasion. But he's also a guy that's a sound player, somebody that can be reliable and responsible out there and let those guys do their thing.''

Barbashev, the 33rd overall pick in the 2014 NHL draft, has a résumé that includes three seasons in the Quebec Major Junior Hockey League and two appearances in the world junior championships. He was expected to spend most, if not all, of this season in the AHL.

His 19 goals and 18 assists with Chicago got him a call-up in late January. Barbashev finished the regular season by playing in the Blues' final 16 games, with three goals and six assists. In addition to being one of the team's most productive five-on-five players, Barbashev shows equal savvy and enthusiasm on defense, giving Yeo confidence that the Moscow native can match up against anyone.

That helped tip the balance when Yeo was pondering line combinations for the playoff opener. The absence of center Paul Stastny, sidelined by a lower-body injury, and the return of winger Vladimir Sobotka from Russia's Kontinental Hockey League prompted some shuffling. In search of trios that could score and defend, Yeo chose to move Alexander Steen — who had been centering the top line — to right wing on the third line, confident that Barbashev was ready for a top-six role in the postseason.

Blues captain Alex Pietrangelo agreed. "It's not like he's just being thrown into the fire,'' Pietrangelo said. "Obviously, the heat turns up here in the playoffs, but he's been a good player for us. I think it's a great opportunity for him.''

That opportunity, Barbashev said, is all he wanted during a season that has surpassed his wildest dreams.

"I was hoping to get called up and get at least a game or something,'' he said. "I think [Yeo] saw something in me, and I've just been trying to work hard. It's just great that he's given me a chance.''