Upton connected for a two-run home run in the third inning off Mariners left-hander J.A. Happ. Happ allowed five earned runs on eight hits in 3 2/3 innings with three walks and three strikeouts on 80 pitches.
"It's Spring Training. It wasn't very pretty. I think we all know he's better than that," said Mariners manager Lloyd McClendon. "His pitches were up. He had no command. Those things happen."
Smith's home run came off Padres right-hander Andrew Cashner. Cashner allowed three runs in four innings. He walked two and struck out four and got stretched to 82 pitches.
The Padres also got two hits from Will Middlebrooks.
Up next for the Mariners: Taijuan Walker continues his quest for the fifth-starter spot as Seattle hosts the Cubs in a 7:05 p.m. PT game at Peoria Stadium. The 22-year-old right-hander has yet to allow a run while giving up four hits with three walks and 13 strikeouts over 12 innings in four Cactus League starts. Relievers Danny Farquhar and Charlie Furbush are slated for relief in a game that will be televised live on ROOT Sports and MLB.TV.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.