NEW YORK -- In good times and bad, CC Sabathia can usually find something to smile about. His grin has been a staple of the Yankees clubhouse since the day he arrived a decade ago, but following Friday night's abbreviated start against the Athletics, that smile was nowhere to be found.

For the fourth time this season, Sabathia was placed on the 10-day injured list for right knee inflammation. The Yankees recalled right-hander Jonathan Loaisiga from Triple-A Scranton/Wilkes-Barre to take the lefty's place on roster on Saturday.

Sabathia was in pain Friday, his troublesome right knee delivering a knockout punch that Oakland couldn't during his three innings of work in the Yankees' 8-2 loss at Yankee Stadium. The knee has been giving him trouble for several years now, but his demeanor was different as he discussed this latest setback.

"It's frustrating, for sure," Sabathia said. "Especially because I feel like I can still get outs and help the team. The hardest part is not being able to be out there, and when I am out there, I'm not performing. It's frustrating."

Looking as dejected as he has in years, Sabathia spoke matter-of-factly about the ailing knee, which has been a source of concern for him for more than five years.

"It just got bad again," Sabathia said. "I threw a pitch in the third inning and just felt a lot of pain."

Asked what his level of pain was compared to his previous problems this season, Sabathia responded, "It's a 10."

At the age of 39, with a résumé chock full of accomplishments that include 251 victories, 3,082 strikeouts and a World Series ring, Sabathia is planning to retire at season's end. But while he knows he's no longer the 200-inning horse he was during the peak of his powers, the idea of limping off the mound at the end of August for his final big league appearance seems unfathomable to him.

"I'm not worried about it," he said when asked about the calendar, which flips to September on Sunday. "I'm just going to wait until I'm healthy. Whenever that is, it is."

Sabathia will have the knee drained Saturday -- with a cortisone injection, synthetic lubrication or both likely to follow shortly thereafter. The Yankees have championship expectations this season, and while Sabathia is no longer the top-of-the-rotation ace who can carry the team on his back, his presence -- both on and off the field -- is felt throughout the clubhouse and dugout.

"It's tough to see, especially your leader of the team," Aaron Judge said. "It's his last year, and he wants to finish this thing out strong, but it's tough. We're going to do whatever we can to keep supporting him. Hopefully he can get healthy here and help us down the road. We'll see."

Sabathia said he felt something in the knee during his last start, a four-inning outing against the Dodgers in Los Angeles. Forced to hit under National League rules, Sabathia took a curveball during his third-inning plate appearance, stepping hard on his right leg.

"That started it," he said.

That his latest bout with pain began with a plate appearance didn't bother him.

"It could have been anything" he said. "Walking up and down the stairs. It could have happened at any point. It just so happened I was hitting."

Friday, he felt pain in the knee from the moment he took the mound, but he was determined to give the Yankees everything he had.

He issued a walk and hit a batter in the first inning, but induced an inning-ending double play to escape without any damage. Jurickson Profar got him for a solo homer in the second, but even as the knee flared up and shot pain throughout his body, the big lefty went back out for the third and struck out Marcus Semien and Matt Chapman before retiring Matt Olson.

"I could tell early on tonight that he was struggling with it," manager Aaron Boone said. "The warrior that he is, he pitches as effectively as he did. Even in that third inning, it felt apparent to me and when I told him after the inning, 'That's good,' he knew."

Whether Sabathia is 100 percent or not, it won't be a surprise to his teammates to see him give it another try.

"It just shows you what type of warrior and what kind of competitor CC is," Judge said. "He probably knew even coming back that he wasn't feeling his best, but he's like, ‘I've got to be out there for my team; I'm going to go out there and do what I can.' Even tonight, they wanted to take him out after the first inning and he said, ‘No, I'm not going to do that. Let me go out there for at least one more.' For him to navigate that lineup through that third inning, the guys like Olson coming up, that was pretty impressive."

Sabathia doesn't know when he'll be back on the mound, and although he appeared discouraged following Friday's abbreviated outing, he remains determined to return to the mound and do what he can to help the Yankees in their drive for a 28th championship.

"That's the plan," Sabathia said. "Hopefully I can just get enough rest where it will calm down and I'm able to get back out there and throw 90-100 pitches."