Chris Smith became the oldest first-time starter in A's history at age 36, but wound up with a no-decision after giving up six hits and three runs in six innings.
Alonso hit his 20th homer of the year in the third for the A's and Marcus Semien gave the A's a 3-2 lead when he just cleared the fence in left field for his fourth home run of the season in the fifth, before Seattle tied the game back up with a homer by Jarrod Dyson.
Dyson went 2-for-3 and scored twice and shortstop Jean Segura had a pair of doubles and an RBI in a 2-for-4 night that puts his average at .