Nava's fifth-inning single extended his streak of reaching base safely to 14 games. He's hitting .500 (16 for 32) this spring with nine RBIs.
Santiago gave up five runs, three in the seventh, and six hits. He walked one and struck out four.
Oakland starter Kendall Graveman gave up four runs and eight hits over 5 1-3 innings.
"I felt locked in and got deeper in the game," Graveman said. "And I kept the walks down. On that pitch to Simmons, I've got to limit the damage."
Athletics: Graveman felt good about his changeup and getting Albert Pujols to ground into a double play. The right-hander didn't feel as good about giving up a two-run homer.
"I got some weak contact with the changeup," Graveman said. "That was good. I'm using it more, trying to get more comfortable with it. I threw a lot of quality pitches. We gave up a couple and I came back to get a double play and get out of the inning. It was good against a good hitter like Pujols."
Angels: Santiago experimented with a few pitches during the game, settling on the slider as one of his go-to pitches.
"I threw a bunch of sliders to both lefties and righties," he said. "Last year, the pitch would be hit or miss. Now, I feel confident using it."
Santiago threw all six of his pitches, and most of them were effective. The screwball, a pitch he learned while developing his changeup, didn't make the transition from the bullpen to the game.
"I threw five of them, none over the plate," he said. "In the bullpen it was there, but with hitters maybe I tried to make it better than I needed it to be."
Athletics: RHP Henderson Alvarez was scheduled to play catch and throw about 35 pitches. He's expected to throw every Tuesday and Saturday for now. ... OF Sam Fuld traveled to Los Angeles for a second opinion on his injured shoulder.
Angels: INF Yunel Escobar was scratched from Wednesday's starting lineup with left eye irritation.
The Angels were also supposed to play a split-squad game Tuesday in Salt Lake City at the home of their Triple-A affiliate, the Salt Lake Bees. But the game was canceled because of snow.