But it was the hit Johjima absorbed in the fifth inning from San Diego's Josh Barfield on a play at the plate after a throw from right fielder Ichiro Suzuki that gave Seattle as big of a lift as any of the three home runs that it hit.
"That play swung the momentum back to our side," Seattle manager Mike Hargrove said. "Ichiro and Kenji played it to perfection."
With one run in and the bases loaded in the fifth inning, the Mariners were clinging to a 3-2 lead when Brian Giles lifted a one-out fly ball to Ichiro.
Barfield tagged up as Ichiro caught the ball in mid-right field and then fired a strike on the fly to Johjima, who had the plate blocked.
The 6-foot, 190 pound Barfield barreled into Johjima, who was sent tumbling backward. When the dust settled, Johjima still had the ball, Barfield looked miffed and the Mariners still had the lead.
"The throw by Ichiro was huge," Mariners starter Jarrod Washburn said. "[Johjima] took it well. I don't know if he's been hit that hard before. I'm sure he'll remember it."
Tools of ignorance? Ichiro said he'd much rather have made the throw than the tag in that sticky situation.
"If I was a catcher," Ichiro said, "I'd run away."
But these were precisely the kinds of plays the Mariners envisioned Johjima making when the signed him to a three-year contract for $16.5 million in November.
The Mariners wanted stability behind the plate after using seven different catchers in 2005. They wanted a catcher who could drive in runs. They also wanted a catcher with defense on the brain.
They've gotten all three in Johjima, who is hitting .288 with four home runs and 21 RBIs this season. He's also appeared in all but three of the Mariners' 43 games this season.
Jose Lopez had a few good knocks of his own on Friday with a solo home run in the third inning off Padres starter Chris Young and then what amounted to the game-winning hit in the seventh inning.
Yuniesky Betancourt started the inning with a single off reliever Scott Cassidy (3-2) and then promptly stole second base. When catcher Josh Bard's throw sailed into center field, Betancourt advanced to third base.
Ichiro -- who had a hit to extend his hitting streak to 13 games -- then reached on an error.
That brought up Lopez, who has made it a priority since Spring Training to hit the ball up the middle and to right field -- two things he didn't do last season, which earned him a demotion to Triple-A Tacoma.
But Lopez took a fastball the other way from Cassidy, lining it into the right-field corner for an RBI double that gave the Mariners a 4-3 lead.
Hargrove said that hit -- and not Lopez's sixth home run of the season -- impressed him the most.
"That showed patience ... he took what the pitcher gave him," Hargrove said. "He's been fun to watch. I think it's still too early to say that he's emerged as a clutch hitter, but we're well down that road."
Lopez leads all Major League second baseman with 33 RBIs and 54 hits. He's hit in 15 of his last 17 games and, for a team that often struggles to score runs, remains the offensive bright spot.
Seattle reliever Rafael Soriano (1-1) allowed one run over two innings to earn his first victory since Aug. 29, 2003.
Washburn, who allowed two runs on five hits over six innings, was in line for the victory before Soriano allowed a game-tying home run to Bard in the seventh inning.
Aside from Lopez and Johjima's offensive contributions, Richie Sexson blasted his fifth home run of the season. Every player in the starting lineup had at least one hit.
Not a bad night on the opening of Interleague Play, especially for Johjima, who was asked after which gave him the biggest thrill -- the home run he hit or hanging onto Ichiro's throw after the collision.
"If I had to choose one, I'd have to say both," Johjima said, smiling. "They're both my jobs."