NORTH PORT, Fla. -- With Chris Sale’s return date now undetermined, many are expecting Eduardo Rodriguez to step up in his absence and become the staff ace.

While it’s a title Rodriguez hasn’t officially worn before, Red Sox interim manager Ron Roenicke has news to break: Rodriguez has been an ace for a while.

“He kind of pitched his way into No. 1 last year, so whether he’s the No. 1 on our staff or just a No. 1 [doesn’t matter],” Roenicke said Friday, before the Red Sox fell to Atlanta, 7-5, at CoolToday Park. “You get Sale back, there’s two No. 1s.”

If there’s any pressure on Rodriguez this spring, it’s certainly not coming from the organization. After weathering some growing pains in 2018, the 26-year-old posted career bests across the board last season with a 19-6 record and 3.81 ERA in 34 starts thanks in part to 213 strikeouts in 203 1/3 innings. Rodriguez’s exit velocity (94th percentile) and hard-hit rate (96th) ranked among the league’s best, and Roenicke said the lefty even had matured enough that he’s emerging as a bit of a leader to some the other Latino players.

In short: "You saw the pitcher that we all hoped he could be and had a fantastic year,” Roenicke said.

With Rodriguez coming off the high of last season, all the Red Sox are asking him to do is hold course. Early as it is in spring, he’s right on track. Rodriguez faced Braves’ "A" lineup for four innings on Friday and scattered three hits: one a solo home run to Austin Riley in the fourth inning, another a bloop single to shallow left-center field that fell untouched between three fielders.

“Eddie was good,” Roenicke said after the outing. “He really threw some good breaking balls today, too. The fastball and changeup are always there, the cutter is good, but he threw some really nice curveballs. It was nice to see.”

Rodriguez struck out four and walked one, using his offspeed arsenal to induce several swings-and-misses against Atlanta’s powerful bats. He was pleased with all his pitches.

“I’ve been feeling good since I got back from that little knee twist,” said Rodriguez, who took a spill in the bullpen early in camp and tweaked his left knee. “I’ve been feeling good. Everything was working really good. … It was a great four innings for me.”

Friday made it two solid spring starts -- he also fanned six Yankees in his two-inning debut on Feb. 29 -- and a small burden has been lifted from the Red Sox, who learned Tuesday that Sale has a flexor strain in his left elbow. Sale called the blow “a gut punch” after he missed the final six weeks of the 2019 season with discomfort in the elbow.

Boston, in the meantime, was sent scrambling to fill a need in the rotation that will last longer than originally thought, making Rodriguez’s success all the more crucial. The Red Sox added versatile pitcher Collin McHugh on Thursday. The former Astros hurler can slot into the rotation, find a home in the bullpen or bounce between, although he won’t be ready at the start of the season as he tends to a right elbow injury of his own.

Having Rodriguez off to a good start makes the unknowns in Boston a little less frightening. But he’s not worried about expectations. Or the competition. Or what his title will be once Sale returns.

“Everyone’s asked me the same question, and I told them I don’t care if I’m gonna go the first or the fifth; I just want to go out there every five days,” Rodriguez said. “In any spot they put me in, I’m going to go out there and try to do the best I can to win the game.”