SEATTLE -- George Springer hit the first pitch he saw in three days for a home run.
"That's pretty impressive, to sit out a couple games then the first pitch you see, you take it out the opposite way," Astros manager Bo Porter said. "That's definitely good to see."
Springer injured his right hip flexor on a ninth-inning pickoff play Wednesday in Anaheim. He then sat out the first two games of this series, both Seattle victories. But after Jose Altuve walked to open the game, Springer hit a 90 mph fastball from Brandon Maurer (1-3) into the right-field seats.
He also connected on a 1-1 cutter from Maurer for another two-run homer in the Astros' five-run sixth. He added an RBI in the sixth for a career-high five, in his 33rd big league game.
Oberholtzer (1-6), recalled from Triple-A Oklahoma City before the game, allowed two runs in the first and then settled in, retiring 10 straight during one stretch. He finished with three runs allowed -- two earned -- with one walk and a career-high eight strikeouts.
"He did a great job of attacking the strike zone," Porter said. "He did a good job pitching in. When he pitched his first stint here, he had gotten away from his effectiveness, on the inner third of the plate. He got that back today and really attacked both sides."
In his only other start against Seattle on Sept. 1 last season, Oberholtzer threw a complete-game shutout, allowing four hits, walking one and striking out five. He is 2-0 with a 1.20 ERA in 15 innings against Seattle.
"I felt I pitched good," Oberholtzer said. "Before the game, I told myself, whatever happens, happens. Throw strikes and have fun. It's been a while since I've had fun."
Maurer went 4 1/3 innings for the Mariners, allowing six runs on six hits. He walked one and struck out two.
The Mariners rallied for two runs in the bottom of the first inning. Stefen Romero walked, then Robinson Cano singled to right. Cano has reached base safely in 31 consecutive games, hitting .372 with 11 extra-base hits and 20 RBI during the streak. It is the longest streak of his career and longest active in the majors.
Justin Smoak followed with a single, loading the bases for Kyle Seager, who bounced a potential double-play grounder to first. But first baseman Marc Krauss threw wildly to second, allowing Romero and Cano to score.
After Springer's first homer, Maurer then retired the next 11 straight, nine on fly balls. But the Astros rocked him in the fifth.
Chris Carter opened with a double to left and Alex Presley singled to right, with Carter holding at third. Jonathan Villar bounced a grounder to Cano, who tried to start 4-6-3 double play but bobbled the ball and settled for a Presley tagout as Carter scored.
Altuve singled to right, and Villar, running on the pitch, scored from first to make it 4-2. Springer followed with his sixth home run on a 1-1 fastball from Maurer into the left-field bullpen.
"He's unbelievable," Springer said of Altuve. "When he goes, our offense goes. He's always on base. He's a big guy for us. I'm happy to hit behind him and happy to play with him. He can run, and with him on base, it makes it easier for me to be more selective and still aggressive.
"The home runs were all on him. He got me in a good hitting count and we go from there."
Mariners manager Lloyd McClendon said Maurer has had "a few times where he is on a run and one thing or another goes wrong and he doesn't seem to get it back together."
Asked about that, Maurer said: "I lost conviction. I wasn't throwing with confidence in my pitches. I don't know, it just went away, I guess."
Tom Wilhelmsen entered and yielded an RBI single to Krauss as the Astros matched their season high for runs in an inning. It also was the most runs allowed in an inning by the Mariners this season.
The Astros scored two more in the sixth, one on a wild pitch by Wilhelmsen and the other on Springer's RBI groundout. Wilhelmsen had entered with a 13 2-3-inning consecutive scoreless streak.
RHP Taijuan Walker, sidelined since spring training with a sore shoulder, likely will be sent out on a rehab assignment Wednesday. He will start for Triple-A Tacoma and be limited to 75 pitches. "I'm excited to get back there Wednesday, get into my regular five-day routine again," Walker said. Walker is the Mariners' top pitching prospect. Oberholtzer was recalled before the game with LHP Rudy Owens, who started Friday and optioned back to Triple-A Oklahoma City. Astros manager Bo Porter said the spot starts by Oberholtzer and Owens "allows all those guys (regular starters) to get an extra day rest. It just makes good sense to take care of the guys who've been so good for us all year." ... It was a "Turn Back the Clock" night for the Mariners, back to 1979. NBA great Lenny Wilkens, coach of the city's only major championship that year, tossed out the first pitch. Mariners manager Lloyd McClendon caught it. ... James Jones' single in the second extended his hitting streak to 14 games. It's also a continuing club rookie record for his first 14 career starts.