CHICAGO -- New York Mets closer Edwin Diaz is facing a 10-game suspension after he was ejected from Sunday night's 5-2 win over the Chicago Cubs for having an illegal substance on his pitching hand.

Diaz, 30, was thrown out by crew chief Vic Carapazza before he took the mound in the bottom of the ninth inning.

"I touched his hand," Carapazza said in a pool report after the game. "Grabbed his hand. The substance was extremely sticky. Discolored ... it definitely wasn't rosin and sweat. We've checked thousands of these. I know what that feeling is. This was very sticky."

Diaz claimed he uses only rosin, sweat and dirt on his hands.

"I use the same thing, always," he said. "I rub rosin, sweat and I put my hand in the dirt a little bit so I can have some grip on the ball. ... I was really surprised because I didn't have anything on my hand, glove or belt. They always check everything."

Carapazza confirmed there were no sticky substances on Diaz other than on his hand, but that's enough to get a player ejected. In recent years, Major League Baseball has cracked down on pitchers using foreign substances other than rosin because they allow for better grips and more spin on the ball.

Carapazza added that the Mets really didn't argue the ejection or explain what happened.

"I told them I have a job to do," Carapazza said. "We're supposed to check it, and that was too sticky. I can't ignore the substance that was on there."

Diaz now faces an automatic 10-game suspension for use of an illegal substance. He can appeal but said he isn't sure if he will.

"It's tough to let my teammates down for 10 games," Diaz said. "That sucks."

Mets manager Carlos Mendoza lamented the loss of Diaz; by rule, the Mets have to play short a man for the length of the suspension.

"We have to move on," Mendoza said. "Guys are going to have to step up."

Drew Smith and Jake Diekman did that Sunday night, combining to pitch a scoreless ninth inning after Diaz was tossed as the Mets won for the ninth time in 11 games.

Diaz has struggled this season, with just seven saves and a 4.70 ERA. He missed all of last season with a knee injury suffered while celebrating a Puerto Rico win in the World Baseball Classic, and spent about two weeks on the injured list this season with a shoulder issue before being reinstated June 13.