Navarro, who entered the game with 12 hits in 42 at-bats (.286), is in his third stint with the Angels this season after spending time in the Minor Leagues.
"I come in prepared, and if I'm hitting leadoff or hitting ninth, it doesn't matter," Navarro said before going 1-for-3 with a third-inning double in the Angels' 12-7 comeback victory. "I have to do my job."
While Angels fans aren't accustomed to seeing Navarro in this role, he does have a bit of experience batting leadoff. Last season, he hit first in the Angels' 3-0 win over the Phillies on May 14, going 1-for-5 with an RBI single.
Angels manager Mike Scioscia said he expected A's starter Sonny Gray to pitch deep into the game -- he worked six-plus -- and that having two consecutive lefties in Navarro and Kole Calhoun against a lefty reliever becomes less of an issue given Gray's track record.
Against right-handers, Scioscia said he could continue to use the Navarro and Calhoun combination going forward, if it works. If a lefty is on the mound, Scioscia indicated he'll likely put second baseman Johnny Giavotella in the top spot.
"Efren's been getting on base for us," Scioscia said. "We'll see if he can at least pass the baton to Kole a couple times and see if we can get our big guys up with some guys on base."
• Albert Pujols batted fourth for the fourth consecutive game Friday. Tuesday marked the first time Pujols batted fourth since April 4, 2003. Pujols entered Friday's action with 11 home runs in his last 19 games.
• Scioscia spoke with Major League Baseball Commissioner Rob Manfred on Friday. They discussed topics such as All-Star voting, instant replay and the direction of baseball.
"Needless to say, Major League Baseball has paid a lot of attention to [replay] because it's such an important change in our game," Scioscia said. "It will evolve. I think everyone realizes that."
• Draft Tracker: Every Angels selection
• The Angels signed 14th-round Draft pick Ryan Vega, an outfielder from El Paso Community College, on Friday. The club has signed 35 players from its 2015 Draft class, including Kyle Survance, Samuel Pastrone, Mitchell Esser, Trever Allen, Conor Lillis-White, Jordan Serena, Thomas Delph, Jacob McDavid, Jahmai Jones and Grayson Long.