BOSTON -- New York Yankees pitcher Michael Pineda has been suspended 10 games by Major League Baseball "for possessing a foreign substance on his person" in Wednesday night's game against the Boston Red Sox.

Pineda said he would not appeal the suspension, which is set to begin Thursday night. He is eligible to return May 5 at the Los Angeles Angels.

"I'll accept it because I know I made a mistake," Pineda said. "That's it."

Pineda was ejected by plate umpire Gerry Davis in the second inning of Wednesday's 5-1 loss to the Red Sox after Boston manager John Farrell complained about a smear of something on the right side of Pineda's neck. Pineda later admitted the substance was pine tar, banned for use by pitchers under section 8.02 of the MLB rulebook, but said he was using it merely to improve his grip on the ball in the blustery, 50-degree weather.

"The truth is that I feel [stupid]," he told ESPNDeportes.com. "It was a last-minute decision when I went out in the second inning, and since I was unable to see myself, I did not know how much I had put on until I saw it on video.

"I put it on my neck because it is a part of my body I always touch when I pitch. I knew there would be cameras there, but because it was a last-minute decision, I did not realize the amount I had put on."

Michael Pineda received a 10-game suspension for having a foreign substance on his neck in Wednesday's start. AP Photo/Elise Amendola

Previously, Pineda had been suspected of using pine tar in a game against the Red Sox at Yankee Stadium on April 10 when television cameras caught a shiny substance on the palm of his pitching hand. That night, Farrell did not protest and no action was taken against Pineda.

"I think there are some things, this being one of them, inside the game that pitchers, particularly in climates like last night, you're looking for some sort of grip," Farrell said. "I think there are probably ways you can be a little more discreet."

Yankees manager Joe Girardi said Pineda had acted on his own during Wednesday night's game, and GM Brian Cashman expressed "embarrassment" on behalf of the organization while saying the responsibility for the transgression was primarily Pineda's.

"Nobody tell me," Pineda said Thursday. "I did it by myself."

Girardi said he thought Pineda understood the seriousness of his action, "but I think he got caught up in the moment of competing and it got the best of him."