LAKE BUENA VISTA, Fla. – He turned 23 in January and has only 34 major league starts on his resume, but Julio Teheran will be be the Braves' opening-day starter, and he and his teammates seem happy about that.

“It’s a great honor to be the starting pitcher opening day,” Teheran said after Braves manager Fredi Gonzalez gave him the news everyone anticipated, that he’ll start the March 31 opener at Milwaukee. “I just want to say thanks for the opportunity. I’ve been working hard and it’s paying off.”

Kris Medlen was the planned opening-day starter before tearing an elbow ligament March 9 and having season-ending Tommy John surgery.

With Mike Minor several weeks behind other pitchers after being shut down early in camp with shoulder soreness, and Brandon Beachy also out for the season after another elbow surgery, Teheran was the logical choice for opening-day starter.

“He just keeps getting better,” Braves manager Fredi Gonzalez said of the Colombian right-hander, who was 14-8 with a 3.20 ERA in 30 starts as a rookie last season, with 170 strikeouts in 185-2/3 innings. “I think he’s mature enough to handle (starting opening day). A lot of guys tell you it’s not that big a deal, but I think it’s a big deal.”

But not too big that Gonzalez couldn’t joke with Teheran before making it official Saturday morning. He called the pitcher into the manager’s office without smiling and asked Teheran what he had done the night before, as if he were in trouble.

“I knew I didn’t do anything wrong; the only thing I do is try to do the right things,” Teheran said, smiling. “I kind of took the joke. He said something like, ‘What did you do last night?’ I said, I slept the whole night, because I was tired.

“I wasn’t doing anything last night, because I was tired. But that was funny.”

The Braves are expected to open the season with a four-man rotation that includes left-hander Alex Wood, rookie David Hale and 37-year-old Freddy Garcia. Gonzalez said he would probably wait a couple of days to announce the full rotation.

They’ll add recently signed Ervin Santana, a former American League All-Star, to the rotation in the second week when they need a fifth starter for the first time. Santana is certainly not a fifth starter, but since he was late signing -- the Braves scrambled to get him after the Medlen injury -- and only pitched in his first game last week, he is building arm strength before joining the rotation.

Teammates were solidly behind the choice of Teheran to replace injured Medlen.

“Absolutely,” Braves catcher Evan Gattis said. “He’s a competititor, man. He executes his pitches, and he’s a winner. He wants to win. He’s not afraid of anybody – at all.”

It would be a understatement to say it’s been an eventful spring training for Teheran, who last month signed a six-year, $32.4 million contract extension with a seventh-year, $12 million option for 2020. He was still two years from being eligible for arbitration, but the Braves gave him long-term security in exchange for a deal that could end up being quite a bargain for the team.

Even if he wasn’t the one originally penciled in for the opening-day assignment, Teheran was long considered the pitcher with the highest ceiling among the Braves’ homegrown young arms. Since early last season he’s pitched like a budding ace.

After going 1-1 with a 6.00 ERA in his first 10 major league games (seven starts), Teheran  is 14-8 with a 2.81 ERA in 27 starts since April 19, with 158 strikeouts and 38 walks in 169-2/3 innings.

He has a 1.42 ERA and .194 opponents’ average in five spring-training starts, allowing 13 hits, three runs and three walks with 17 strikeouts in 19 innings.

“He’s had a great spring,” said veteran backup catcher Gerald Laird, who has seen steady development from Teheran since Laird’s first spring training with the Braves in 2013. “He not afraid of anybody. He’s a competititor, too. He gave up a couple of hits (Friday) and you could tell he was upset. That’s one thing he doesn’t lack, is confidence.”

Teheran’s .217 opponents’ average with runners in scoring position last season ranked eighth among NL starters, and only Clayton Kershaw (.180) was below .202.

“Then main thing I liked about him was how he responded when things didn’t go his way,” Laird said. “That’s a big asset for young guys. It didn’t seem like he ever folded. He’s one of those guys that can step up to the challenge, when guys get on base or a rough inning he was able to calm himself down and continue to make pitches. You saw him get better and better and better throughout the whole season, and that’s the biggest thing.

“A lot of young guys come up here and struggle, then they give in (to hitters), and it kills your bullpen. But he was able to give up runs early and still be able to pitch five or six innings for us. Then he started kind of figuring it out, where he was going five, six, seven innings without giving up those runs.”

Gonzalez said of Teheran's ability to work out of jams: "He would rise up to the occasion. I remember a bunch of times where he’d get (runners on) first and third or second and third with one out, or bases loaded, one out, and get out of it. You’d see his game rise up a little bit.”

Teheran ranked second among major league rookies with 170 strikeouts, behind Miami phenom Jose Fernandez (187). Teheran was also second among rookies in innings (185-2/3), fourth in ERA (3.20) and second in WHIP (1.17).

Gonzalez didn’t say why he was waiting to announce the rest of the rotation, but the Braves perhaps want to make sure Garcia and Hale get through starts Sunday and Monday without health concerns. They also might want to wait as long as possible to make sure no other starting pitcher becomes available on waivers or as an “opt out” free agent.

Garcia, who signed a minor league contract, can opt out of his deal and become a free agent if he’s not added to the Braves’ major league roster by Tuesday.