Seattle Mariners left-hander Yusei Kikuchi threw a gem against the New York Yankees on Wednesday night in hitter-friendly Yankee Stadium.

But he might have benefitted from a little help.

Here’s a video of the pine tar under Kikuchi’s hat. pic.twitter.com/oFgT5700gR — Andrew (@Andrew_Rotondi) May 9, 2019

There appears to have been a foreign substance underneath the brim of Kikuchi's cap.

Yankees manager Aaron Boone said he was made aware of the substance during the eighth inning.

"We'll look at it," Boone said, according to Bryan Hoch of MLB.com.

Kikuchi carried a no-hitter into the sixth inning, finishing the night allowing one run on three hits with three strikeouts and one walk during the Mariners' 10-1 victory.

If he was discovered to have been doctoring the baseball during the game, with pine tar or any other foreign substance, Kikuchi would have faced an immediate ejection and been subsequently suspended for 10 contests, according to the MLB rule book.

Fans from the stands seemed to notice. One was apparently shouting at home plate umpire Angel Hernandez to "check his hat," according to Coley Harvey of ESPN. Hernandez chose to ignore the fan.