SAN DIEGO -- During six of his first seven seasons with the New York Yankees, Mark Teixeira was a key element in the club's offense, topping 30 homers four times and 100 RBIs three times.

However, the 2016 season has admittedly been a struggle for the 36-year-old first baseman, who entered Sunday's series finale against the San Diego Padres at Petco Park with five homers, 14 RBIs and a .187 batting average in 55 games.

After striking out in each of his first three at-bats, Teixeira homered twice against Padres relievers to lead the Yankees to a 6-3 win that prevented San Diego from sweeping the three-game series.

The first homer, a high, 334-foot drive off right-hander Carlos Villanueva that landed in the short porch down the right field line, upped the Yankees' lead to 3-1 and made history. It was the 400th of Teixeira's career, making him only the fifth switch hitter in major league history to reach that mark.

An inning later, Teixeira hit a two-run, 404-foot shot off right-hander Kevin Quackenbush into the stands in right-center. Not only did that shot cap a three-run inning that expanded the margin to 6-1, but it also marked the 42nd time in Teixeira's career that he hit multiple homers in a game.

"We've talked about how important Mark is to our lineup," Yankees manager Joe Girardi said. "He was really important today."

Teixeira said, "The 400th, I didn't know if it was going out because I hit it so high. You didn't know how it was going to carry. But the second one I could enjoy a little bit."

Meanwhile, Padres manager Andy Green was calling into question his team's scouting reports on Teixeira.

"Our reports failed us today," Green said. "Teixeira got us on two breaking balls when the reports said he had been struggling on breaking balls."

Teixeira wasn't New York's only weapon Sunday.

Didi Gregorius put the Yankees ahead to stay with a fourth-inning homer, and he scored the game's first run two innings earlier after reaching base on an error.

Right-hander Chad Green, who was officially promoted from Triple-A Scranton/Wilkes-Barre on Sunday morning, allowed one run -- on a second-inning homer by former Yankee Yangervis Solarte -- on three hits with eight strikeouts over six innings. He picked up his first major league win in his second career start.

New York closer Aroldis Chapman got the final three outs to record his 16th save after Padres left fielder Alex Dickerson followed Solarte's fourth hit of the game with a two-run homer off Yankees reliever Anthony Swarzak to open the ninth. Chapman's fastball topped out at 101 mph.

"We really needed a win today," Girardi said. "Green was really, really good today. He was much more of who we thought he was today than he was in his first start (in May)."

Green was leading the International League in earned-run average before his latest call-up by the Yankees.

"I added a cutter the past couple of weeks, and that made a big difference," he said. "I was just trying to make pitches (Sunday) without trying to do too much."

Green was locked in a pitching duel with the Padres' Andrew Cashner (3-6) over the first six innings.

Cashner, who came off the disabled list Sunday morning to make his first start since June 10, allowed two runs (one earned) on six hits and two walks with six strikeouts in six innings. He had been sidelined since June 11 with a neck strain after missing 16 days on the disabled list in May with a hamstring strain.

"It's frustrating when you get beat, but I can't do anything about that," Cashner said. "I felt good. I had good command of my fastball and slider."

Green said, "I was pleased with the way Cashner threw today. He had good velocity, 97 (mph) on the fastball and 91 on the slider. He did a great job. He deserved to win that game."

The difference between Green and Cashner was an error made by Padres shortstop Alexei Ramirez on a Gregorius grounder leading off the second.

After Ramirez's fourth error in a span of nine games, Gregorius raced to third on the first of three hits by Aaron Hicks, putting Yankees at first and third with no one out.

Gregorius scored the game's first run when Ronald Torreyes grounded into a double play.

Solarte tied the game in the bottom of the second on a 347-foot, opposite-field drive into the first row of seats in left.

Gregorius put the Yankees back ahead at 2-1 in the fourth on a 330-foot drive to right.

The Padres wasted two golden opportunities.

The loss added to a series of statistical irregularities for the Padres, who are now 3-24 in series finales, 6-21 in day games (including 2-9 in day games at Petco Park) and 1-12 on Sundays.

NOTES: Manager Joe Girardi said he is not sure Carlos Beltran (sore hamstring) will be ready to return to the outfield Monday when the Yankees return to American League action at the Chicago White Sox. If Beltran can't play in the outfield, the switch-hitter would be the designated hitter, keeping Alex Rodriguez out of the lineup. ... RHP Conor Mullee, who went on the disabled list Saturday after coming out of Friday night's game in San Diego with numbness in his pitching hand, will see a Yankees hand specialist Tuesday. ... INF/OF Alexi Amarista was optioned to Triple-A El Paso to clear a spot for RHP Andrew Cashner to come off the 15-day DL. ... 2B Cory Spangenberg and 2B Jemile Weeks will report to the Padres' year-round Arizona camp Monday to ramp up rehab efforts. Spangenberg has been on the DL since April 20 with a quad strain. Weeks has been out since May 8 with a hamstring strain.