MESA, Ariz. >> As the A’s rotation takes shape this spring, a number of young, largely-unproven pitchers are vying for an opportunity to log valuable major-league innings this season as well as a chance to establish themselves in the big leagues.

Kyle Muller is no exception.

The 25-year-old left-hander was one of the top players the A’s received in the winter trade that sent catcher Sean Murphy to the Braves. He’s drawn a lot of praise since camp opened and is expected to compete for a spot in the rotation. The former No. 1 overall pitching prospect in the Atlanta farm system spent parts of the past two seasons with the Braves, but despite success in the minors wasn’t able to establish himself in the big leagues.

“All I have wanted this entire time is an opportunity to get comfortable and pitch every five days in the major leagues and see how I stack up against the best in the world,” Muller said Thursday. “I feel like that chance is strong here and I just have to go prove myself.”

Muller was part of a three-team deal that included veteran catcher Manny Piña, as well as fellow top prospects Esteury Ruiz, Freddy Tarnok and Royber Salinas heading to Oakland. The trade reunited Muller with his close friend, Shea Langeliers, another product of the Braves minor league system who arrived in Oakland last season as part of the Matt Olson trade.

Despite having to make the unexpected transition over the winter, Muller said he instantly embraced the opportunity for a fresh start with the A’s.

“I had pretty much grown up there,” Muller said of his time with Atlanta. “I was there since I was 18 to 25. Having everything kind of flip like that in a minute-and-a-half phone call, it was kind of wild. But immediately after I got the phone call (about the trade) I was so excited. I texted Shea immediately and I called my parents and told them.”

The 6-foot-7 lefty logged 49 big-league innings with the Braves over the last two seasons, though his stints in Atlanta were brief. In 12 appearances, 11 of them as a starter, he’s 3-5 with a 5.14 ERA.

Muller spent most of his time the past two seasons at Triple-A , where he produced his best results since he was a second-round pick in the 2016 MLB Draft. He posted a 3.39 earned run average across 79.2 innings in 2021, then followed that with a 3.41 ERA in 134.2 innings last season. Muller collected 252 strikeouts between those two seasons in Triple-A.

Muller says last season was a personal breakthrough.

A’s manager Mark Kotsay would like nothing better than to see the towering left-hander build off his breakthrough 2022 and secure one of the five rotation spots.

“He had success at the Triple-A level for a long period of time,” Kotsay said. “Now it’s time for him to go out and really capture this opportunity that he has to make this rotation and be an impact starter for us.”

Fujinami to make Cactus League debut against old rival Ohtani >> Kotsay announced that rookie Japanese right-handed pitcher Shintaro Fujinami will make his first appearance of the spring on Tuesday against the Angels.

But his highly anticipated debut is perhaps even more significant because it will come against his former high school rival, Shohei Ohtani. The Angels announced their pitching plans earlier in the week.

“That’s Fuji’s day, it just happens to coincide with the day that Ohtani is pitching,” Kotsay said.