Headley's doubles were his first extra-base hits this spring. The third baseman was playing in his third game after being sidelined with a strained right calf.
Non-roster invitee Xavier Nady went 3 for 4 with two doubles and three RBIs for San Diego.
"From the top we had some good swings right through the middle of our order," Padres manager Bud Black said. "Chase's first two at-bats were great left-center, right-center (doubles). It was good to see Chase drive the ball. Nady had good at-bats. Q had one good swing on that homer. Will had a good swing. Collectively from top to bottom, everybody contributed with a hit."
Saunders, signed March 5 to be a rotation candidate for the Rangers, retired only four of his 15 batters. He allowed nine runs and eight hits, including five doubles and a homer.
"Just a little case of the normal spring training dead arm, honestly," Saunders said. "My arm feels great, just no crispness in my pitches. Everything kind of seemed to flutter up there, no kind of snap on my pitches."
Padres: Matt Wisler, the organization's minor league pitcher of the year in 2012-13, made his first start after four relief appearances. He allowed five runs on five hits in 2 2/3 innings. With Josh Johnson out four to five weeks with a forearm strain, Wisler becomes a viable rotation candidate.
"I was hoping to come out and throw a lot of strikes and command the baseball, which I didn't do as well as I wanted to," Wisler said. "I was a little disappointed the way it went, but at the same time you're not terribly disappointed with it."
Rangers: Saunders made 52 pitches in 1 1/3 innings with the Padres going 8 for 13 with two walks off him. He is competing for one of two rotation vacancies.
"I feel confident," Saunders said of chances he would make the club. "They know what I'm capable of. I've shown in previous starts that my stuff is there. They've got to realize this is only my third week. I didn't have the regular amount of time other guys had to prepare."
The Rangers remain optimistic Yu Darvish will be able to start the March 31 opener against the Phillies, but because of a stiff neck it appears doubtful he will pitch in a game again before the club breaks camp Wednesday.
"I think we've got to wait and see how this issue progresses," Rangers manager Ron Washington said. "If not, we'll go to a contingency plan. But I don't want to say what that is yet. We still got a little time, so hopefully in a couple days this issue he has clears up."
Washington would like for Darvish to throw an extended bullpen before exiting Arizona and pitch an inning or two in one of the Rangers' exhibition games Friday or Saturday in San Antonio.
Padres: Right-hander Joe Wieland, who had Tommy John surgery in July 2012 and rehabbed last year, will have an arthroscopic procedure on his pitching elbow Tuesday in hopes of fixing the irritation in the back of the elbow.
Rangers: Second baseman Jurickson Profar will be out 10 to 12 weeks with a muscle tear in his right shoulder. Catcher Geovany Soto left in the second inning with discomfort in his right leg, which locked up. He was sent for a precautionary MRI.
RANGERS WIN APPEAL
Washington won his appeal after plate umpire Allen Bailey called Martin out at home to end the third. Replays showed Martin beat the tag and the call was reversed.