BOSTON -- After the Orioles lost to the Red Sox in Game 1 of Saturday’s doubleheader, the O’s had a celebration to attend. Quickly vacated was the visitors’ clubhouse. Joey Krehbiel had a large white cardboard box in his hand, leading a small conga line of Orioles players to the family area at Fenway Park, where it would meet its twin box.

Inside each was a sheet cake, one themed after the movie “Cars,” the other after a Ferrari. Those are Mikael López’s favorites. It was his ninth birthday, after all, and his father, Orioles reliever Jorge López, wanted to make the day special.

Just days prior, Mikael, battling a pair of chronic illnesses that have kept him inside patient rooms much of his childhood, had been cleared to leave Cincinnati Children's Hospital to join his papá in Boston. On the field, Jorge celebrated his son’s first game in person in three years with a four-out save to seal the Orioles’ win in the nightcap, 4-2, over the Red Sox.

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Back in the bowels of Fenway Park hours earlier, Jorge had procured a surprise party for Mikael, with the entirety of the Orioles’ clubhouse there to celebrate. It’s a moment that, not long ago, he wasn’t sure he’d have the chance to savor.

“Really emotional,” López said. “It's been really tough for him. I mean, all his life has been about, always, his condition.

“I don't have words to describe how good the emotions are.”

The chances for Mikael to enjoy a day like Saturday had long been uncertain. Mikael is battling a pair of chronic autoimmune diseases (familial Mediterranean fever and Crohn’s). He has undergone chemotherapy in the past and received a bone marrow transplant in July, which forced López to miss time last season.

And then add in the backdrop of what was required for Mikael to make it to Boston.

Cleared to leave the hospital early in the week, his overall condition improving, Mikael and López’s wife, Karla, flew from their home in Ohio to Baltimore. As storms hit the mid-Atlantic on Thursday and Friday, their flight to Boston was canceled. Karla packed up the car and drove to Philadelphia, where they met a new flight.

They made it in time for Friday’s game. Mikael made the rounds of the clubhouse, fist-bumping players, coaches, media members and clubhouse attendants, wanting to “run all the bases, run on the field. He was just getting crazy,” López said.

Mikael got to see his father pitch that night as well, Jorge providing a breezy final inning to cap off the O’s remarkable 12-8 comeback win over Boston.

But Saturday -- pitching on Mikael’s birthday, entering the game in the eighth inning with a runner in scoring position in a save situation, clinching the Orioles win in the ninth, and having Mikael watch him warm up in right field -- that was a far different emotion.

“[When I first saw that] he was coming, I had so much beat in my heart,” López said, later adding: “I didn't want to [mess] it up right in front of him.”

It shouldn’t have been a surprise that he didn’t. Saturday was his sixth save this season to go along with a 1.16 ERA. It’s been a revelatory year for López, moved to the closer’s role after years of struggling to stick as a starter. Where there was once uncertainty, there’s now conviction.

“You can just tell by the look in his eye when he goes out there,” said Orioles manager Brandon Hyde, “it's all business.”

López has been open about how the stress of being away from Mikael has followed him to the mound. He credits Karla for ameliorating much of those concerns, the family rock through all the appointments and operations, as Jorge has had to mostly support from afar.

Saturday was as much a celebration of the day itself as it was of the year being had in the López household.

“I have to do this for them,” Jorge López said. “He just [had] such a birthday today, and even better with a save and better win. It's a gift for him. He's not gonna forget this for all his life.”

López had returned to his hotel from Friday’s win with a celebratory air. Mikael might have felt it more. He couldn’t fall asleep, the clock approaching his birthday. To tire him out, Jorge broadcast for him a replay of that night’s game, all 3 hours and 38 minutes of it.

They didn’t fall asleep until 4 a.m., enjoying the rare moment as a family that was not marked by doctors and dimly lit hospital hallways. They might not fall asleep at all on Saturday night.

“He’s been unbelievable with us. It's something that we just trust the process and all the meds they've been doing with him, all the doctors,” López said. “It’s so much thankful we have to be as a family, to just have him alive here with us.”