KANSAS CITY, Mo. (AP) — Kansas City starter Yordano Ventura has left their opener in the seventh inning with a cramp in his right thumb.

It was a scary moment for the Royals on Monday when the young ace crumpled to the ground in pain days after agreeing to a $23 million, five-year deal. But the team said shortly after that the injury did not appear serious.

After throwing a strike to Chicago's Adam LaRoche, Ventura initially showed no discomfort. Then suddenly his face contorted in pain, and he flung away his glove. Manager Ned Yost and trainers rushed to the mound.

The 23-year-old Ventura had limited the White Sox to one run and four hits in six-plus innings in his first opening day start.

The hard-throwing right-hander dazzled as a rookie last season, going 14-10 with a 3.20 ERA.