Seattle Mariners first baseman Mike Sweeney take batting practice Friday in Peoria, Ariz.

PEORIA, Ariz. ? Mike Sweeney has every good reason to be a buzz kill.

Amid the Mariners’ euphoria over Ken Griffey Jr.’s return is Sweeney, a five-time All-Star trying to become Seattle’s designated hitter. He stands to lose the final chance of his career with Griffey and his 39-year-old legs in Seattle.

Yet it is more likely Griffey will get booed in gaga Seattle than Sweeney will hold a grudge. The 35-year-old is one of the most respected and just plain liked guys in baseball.

Mariners manager Don Wakamatsu calls Sweeney “an adder. He walks into a room and makes three or four people better.”

Sweeney was taking batting practice when he let a good pitch go past from bench coach Ty Van Burkleo.

“Oh, sorry Ty,” Sweeney said.

A veteran apologizing to a rookie assistant for having wasted his BP pitch? That happens on a major league field about as often as a meteor landing.

“I’m excited. I mean, gosh, anybody would love the chance to play with Ken Griffey Jr. He’s one of the greatest to ever play the game,” Sweeney gushed when asked about Griffey taking away his at-bats — and perhaps his livelihood.

Sweeney is a career .299 hitter who became an All-Star over 13 years in Kansas City. He says he may retire to his family in San Diego rather than try to find another team if he doesn’t make the Mariners.

The Mariners already have decided Griffey will be in left field when his legs feel fine. When baseball’s active leader with 611 home runs says he needs a break, he’ll be the DH.

Since he is coming off arthroscopic knee surgery in October, Griffey could be the DH a lot.

To which Sweeney says, so what?

He’s healthy again, after a back injury in 2006 and surgeries on both knees last June while he was with Oakland seemed to end his career. He’s hitting well enough to impress Wakamatsu so far in camp.

“He’s beautiful,” Wakamatsu said. “And it’s as genuine as can be.”

Sweeney is cackling and joking through batting practices, as if he’s been here for years rather than one week. After a set of swings, he playfully jabbed the knob of his bat like a sword into the stomach of second baseman Jose Lopez. Both laughed.

“I really don’t care if it costs me,” Sweeney said of Griffey’s arrival. “I just want to make the team. If I’m healthy and have done my best, I’ll have no regrets.”

The biggest source for Sweeney’s self-assurance: He says he’s played clean.

Beginning when his neck and back began bothering him in 2002, Sweeney said teammates would tell him he should take a certain illegal substance, and he would be back playing in no time. Sweeney says he always stood by his convictions that such a shortcut was “just not right” and would cheat himself.

“Fans speculate that all players are doing it. It’s unfair to the guys like myself who never did squat — never took a ‘greenie,’ never cheated, never took growth hormone, steroids, none of that,” Sweeney said.

So if Griffey’s return means his exit from baseball while just shy of being a career .300 hitter and one home run away from 200, Sweeney will be fine.

“(I’m) able to look myself in the mirror for the rest of my life and know that everything on the back of the baseball card is 100 percent me, rather than hit 500 home runs and not being able to look myself in the mirror the rest of my life knowing I cheated the game,” he said.

“I’m proud of my career.”