Ohtani went deep into the seats in right-centre field in the seventh inning off Giants left-hander Taylor Rogers in his ninth game of the season, ending the longest season-opening homer drought of his major league career. Ohtani finished 2-for-4 with two runs.
The Dodgers have scored at least five runs in all nine games this season to extend their franchise record and move closer to the New York Yankees' record of 13 games in 1932.
Tyler Glasnow (2-0) won for the second time in three starts and Miguel Rojas added a home run as the Dodgers finished 6-1 on their first homestand of the season.
Red Sox 1, A's 0
Nick Pivetta teamed with four relievers for an eight-hit shutout as Boston completed a three-game sweep at Oakland.
Enmanuel Valdez lifted a sacrifice fly in the fourth inning for the game's only run, allowing Pivetta (1-1) to earn the win in a pitchers' duel with Oakland's Ross Stripling (0-2).
Pivetta limited the A's to five hits in five innings, and Kenley Jansen escaped a ninth-inning jam for his second save. Stripling allowed eight hits and one run in seven innings.
Astros 8, Blue Jays 0
Yordan Alvarez homered twice and finished with four hits and three RBIs as Houston beat visiting Toronto in the rubber match of a three-game set.
Jose Altuve and Jeremy Pena also went deep for Houston, while Cristian Javier (1-0) gave up one hit in five innings. The Astros outhit the Blue Jays 15-1, though Houston pitchers issued seven walks.
Chris Bassitt (0-2) allowed four runs on nine hits in 4 1/3 innings for the Blue Jays.
Guardians 8, Mariners 0
Jose Ramirez hit two doubles and had two RBIs and Logan Allen pitched 6 2/3 scoreless innings as Cleveland routed host Seattle.
Leadoff hitter Steven Kwan went 3-for-5 and scored three times for the Guardians, who took two of three games in the series. Allen (2-0) allowed four hits, walked three and struck out six.
Mariners starter George Kirby (1-1) lasted just 3 2/3 innings and was tagged for eight runs on 10 hits.
Angels 10, Marlins 2
Miguel Sano reached base four times, Patrick Sandoval rebounded from a forgettable Opening Day start and Los Angeles completed a three-game sweep of host Miami.
It was the Angels' fourth win in a row, while the Marlins are now 0-7, the longest losing streak to start a season in franchise history.
AJ Puk (0-2) threw four innings, allowing four runs (two earned) on five hits and three walks, striking out five for Miami.
