Houston had its modern-day record of 10 consecutive Opening Day wins snapped.
Orioles 10, Red Sox 9Adley Rutschman's 5-for-5 Opening Day helped Baltimore to a win over host Boston.
Mets 5, Marlins 3Brandon Nimmo's three RBIs backed Max Scherzer's quality start, leading New York to an Opening Day victory over Miami.
Twins 2, Royals 0Pablo Lopez and four relievers combined on an Opening Day two-hitter as visiting Minnesota blanked Kansas City.
It was O'Neill's fourth consecutive Opening Day with a homer, tying a major league record.