Yankees left-hander Nestor Cortes admitted he was "upset" over being used as a reliever against the Cubs, saying he was surprised by the demotion from New York's starting rotation but that he would accept the new role if it ends up being permanent.

Cortes, a former All-Star who has worked exclusively as a starter since midway through the 2021 season, pitched 4 1/3 no-hit relief innings Saturday afternoon at Wrigley Field, combining with starter Clarke Schmidt for a four-hit shutout in the Yankees' 2-0 victory.

The outspoken Cortes did not mince words after the game, calling himself the "workhorse" of New York's rotation and citing the Yankees' decision to name him as their Opening Day starter when ace Gerrit Cole was sidelined with an elbow injury to start the season.

"Obviously I was upset," Cortes said. "I felt like I've been, amongst all the starters, the workhorse here. Once Cole went down, they picked me to be the Opening Day starter -- not necessarily the No. 1, but the Opening Day starter. I had to switch my routine there.

"Now they do this."

It was the first relief appearance since July 23, 2021, for Cortes (9-10), who lowered his ERA to 3.97 and leads the Yankees with 163 1/3 innings pitched this season. He needed just 48 pitches to complete his outing Saturday, walking one and striking out three.

"I'm never going to back down from a challenge," he said. "I'm never going to leave my teammates out to dry. You're always going to get my best effort, no matter if I'm happy or not.

"That's what I did today. I came out there and proved I can be put in any situation. From here on out, if that's my role, then I'll accept it."

Cortes is scheduled to start one of the Yankees' four games next weekend against the Boston Red Sox, but his role going forward is uncertain as New York is set to revert to a five-man starting rotation.

Cortes, 29, struggled in his most recent start last Sunday, allowing five runs over just four innings in a loss to the St. Louis Cardinals. But he was outstanding in his previous three starts, yielding only one run while striking out 18 over 20 2/3 innings during that stretch.

Yankees manager Aaron Boone praised Cortes for his performance out of the bullpen, saying it was "a testament to being a professional."

"I'm sure he wasn't thrilled about it this turn around," Boone said. "But you still got a job to do, and he went and excelled at it."

Cortes ultimately could be the Yankees' odd man out, however, with Schmidt and Luis Gil both returning from the injured list to rejoin a rotation that includes Cole, Carlos Rodon and Marcus Stroman.

"I have no idea," Cortes said when asked about his role. "This one caught me by surprise, so we'll see.

"I know they told me that I'm starting against Boston, but after that, with a six-man rotation and off days in between, guys are going to get extra days and I don't think that's necessarily the right move, so we'll see."