SEATTLE — Late Wednesday morning, Joe Girardi acknowledged the obvious.

Not only about Gary Sanchez, about whom he was speaking, but any rookie in the majors.

“I’m sure he’s going to have some bumps in the road here,” the Yankees manager said.

They did not occur Wednesday afternoon.

Sanchez homered in his first at-bat of the day and helped back a second straight terrific outing by Masahiro Tanaka, who threw seven shutout innings in a 5-0 victory over the Mariners in front 41,536 at Safeco Field.

“I’ve never seen a young player do what he’s done,” Girardi said after watching Sanchez go 2-for-3 with a homer and a double and two intentional walks. “This is pretty remarkable.”

advertisement | advertise on newsday

The victory gave the Yankees (65-61) a series win over the Mariners (68-58), a 4-2 record on this West Coast trip, Girardi his 800th victory as Yankee manager, and sent the Yankees into Thursday’s off day feeling very much in the thick of the AL wild-card race though, at the moment, still a bit of longshot.

Of course, if the 23-year-old Sanchez keeps this up, who knows what might be possible?

The rookie catcher, who entered the day with a .517/.588/1.207 slash line, with six homers and nine RBIs in his previous eight games, hit a home run to left in the first and a double to left in the fifth. He also was intentionally walked twice, each time to get to Mark Teixeira.

The first time came in the seventh with Brett Gardner on second and one out, leading to an RBI single by Teixeira that made it 4-0.

It happened again with runners at second and third and none out in the ninth, leading to Starlin Castro’s one-out sacrifice fly to make it 5-0.

Yankees videos

“Shoot, if Babe Ruth’s hitting behind him, you intentionally walk him,” Teixeira said of Sanchez. “I mean, he’s as hot as any player I’ve ever played with in my entire career. You just don’t see guys doing what he’s doing, I don’t care how old he is.”

Did Teixeira take insult watching the Mariners intentionally walk Sanchez to get to him?

“I’m hitting .195,” said Teixeira, who is now hitting .197 after going 1-for-4 Wednesday, with a laugh. “Of course you walk him there. C’mon, guys.”

Said Sanchez of the two intentional passes: “I definitely was not expecting that . . . it’s part of the game, I guess. I’m hitting the ball well so I see why they walked me.”

Sanchez blasted the first pitch he saw from Hisashi Iwakuma (14-9), an 86-mph fastball, and sent it into halfway up the second deck in left. It marked his ninth home run in his last 44 at-bats and gave Tanaka 1-0 lead.

advertisement | advertise on newsday

Sanchez became one of nine players in league history since 1913 to record 15 or more extra-base hits in his first 21 games, with Joe DiMaggio the only other Yankee to accomplish the feat. DiMaggio had 17 extra-base hits in 1936.

“Outstanding and astonishing,” Tanaka said, through his translator, of Sanchez’s recent run.

Tanaka, of course, did more than his share to contribute to the victory.

Coming off 7 2⁄3 shutout innings last Friday in Anaheim, he was hit harder than in that outing Wednesday, but was every bit as effective.

The righthander, in improving to 11-4 with a 3.11 ERA, allowed six hits. He walked one and struck out five in recording an AL-best fifth start this season of at least seven innings pitched and zero runs allowed.

advertisement | advertise on newsday

“I think I was overthrowing the first couple of innings,” said Tanaka, who has won his last four starts. “But after that I was able to adjust.”