NEW YORK – The Yankees will begin their postseason drive without Nestor Cortes, who was placed on the 15-day injured list with a left elbow flexor strain on Wednesday, hours before he was scheduled to start against the Orioles at Yankee Stadium.

Cortes said that he has been dealing with tenderness near his elbow for about three weeks, but he experienced discomfort while tossing a bullpen on Sunday at Oakland, which prompted the left-hander to undergo an MRI on Wednesday.

He said that he is hopeful a combination of rest and rehab could permit him to return if the Yankees have a deep playoff run; for now, Cortes will be shut down from throwing for seven to 10 days and is set to receive a platelet-rich plasma injection.

“The mentality and the way I’m going to go about it is to come back, depending on how far we go and how well I do with the rehab,” Cortes said. “Obviously, my main focus is to be able to come back and help this team.”

Cortes said that though his ulnar collateral ligament is believed to be intact, Wednesday’s imaging will be sent to specialists Dr. Neal ElAttrache and Dr. Keith Meister for additional opinions.

Though he stopped short of saying he was optimistic, Yankees manager Aaron Boone is not ruling out the possibility of having Cortes return at some point in October.

“He’s been throwing the ball so well and has put together a really good year,” Boone said. “We certainly feel for him right now. We just have to pick up the slack and support him right now, and then see what we have over the next several days.”

With the Yankees hoping to clinch the American League East on Wednesday, right-hander Marcus Stroman stepped in to take Cortes’ place in the rotation. Right-hander Cody Poteet was also called up from Triple-A Scranton/Wilkes-Barre.

“He’s ready to go, excited to get the ball,” Boone said of Stroman. “He’s been great through all of this. He’s been ready for whatever role comes his way. He’s had a really good year for us and he’s a big reason why we’re in this position.”

Cortes landed on the injured list one week after he pitched six scoreless innings to help the Yankees to a postseason-berth-clinching 2-1 win over the Mariners at T-Mobile Park, solidifying his case to be part of the team's October rotation.

He allowed just one earned run in his last 15 1/3 innings and did not allow more than one earned run in six of his past seven outings. Cortes’ regular season concludes with a 9-10 record and a 3.77 ERA in 31 appearances (30 starts), tossing a career-high 174 1/3 innings.

“It sucks that I’m in this position right now to where I can’t help the team,” Cortes said. “With what I dealt with last year and how well I prepared this offseason, and how well it’s been going for me, it finally felt like things were clicking for me.”

Once the Yankees advance to the postseason, Gerrit Cole and Carlos Rodón seem assured of starting the first two games, while Luis Gil and Clarke Schmidt could either start or pitch out of the bullpen.

Stroman’s move to the bullpen earlier this month suggested that his postseason work would come in a relief role, though that may change depending on how he pitches Wednesday.