PEORIA, Ariz. – Now that Ken Griffey Jr.’s swollen knee has calmed down, he is ready to play in his first game for Seattle in a decade.

The 39-year-old slugger hit for about 10 minutes against two Class A pitchers in a simulated game on Monday. Mariners manager Don Wakamatsu then confirmed Griffey will make his spring debut, as planned, at designated hitter on Wednesday night against Australia’s national team.

The outing will come 11 days after baseball’s leading active home run hitter signed an incentive-filled deal to return to where his career began 20 years ago. Griffey had arthroscopic knee surgery in October.

Griffey was icing his propped-up left knee after workouts a few days ago, then spent the weekend with his wife and children, who were in from Florida.

On Monday, he let a few initial pitches from wide-eyed, 24-year-old Jake Wild go by before he lofted fly balls while Wakamatsu and general manager Jack Zduriencik watched.

Veteran Mike Sweeney, trying to make the team after operations on both of his knees last summer, first baseman Russell Branyan and shortstop Yuniesky Betancourt also hit to keep themselves sharp. All but Branyan have yet to play in a spring game.

“That’s all I need,” a smiling Griffey told his manager after the short session.

“Junior did great,” Wakamatsu said. “There was some swelling in the knee a couple of days ago, but everything’s good now.”

Wakamatsu has said he wants Griffey to have about 30 or 40 at-bats before the opener on April 6 at Minnesota. And Griffey says he doesn’t need games to get that work, adding that spring games are primarily for pitchers.

He will get more swings in another simulated game planned for Friday, and Wakamatsu may put Griffey in minor league games later this month just to keep his swing sharp.

“There are no restrictions on him,” Wakamatsu said, reiterating the Mariners are trying to preserve Griffey for the entire season.

“(During the season) it’s going to be the plane flights, if he has to slide in games, playing the field a lot. We’re going to be cognizant of all that and monitor as we go along,” Wakamatsu added.