Mariners manager Jim Riggleman is trying his best not to allow Kenji Johjima, Jose Vidro and Richie Sexson to get lost in a Bermuda Triangle of at-bats.

Johjima has lost his regular catching job to Jeff Clement and Riggleman hopes to keep his swing in tune with regular duty at designated hitter.

That creates a problem for switch-hitting Vidro, who has started 52 of the Mariners’ 82 games at DH. Riggleman’s solution for that is to play Vidro at first base.

Problem with that is Sexson.

“It’s a situation where we try to keep both of them sharp, but I can’t put both out there at the same time,” Riggleman said of Vidro and Sexson. “If I play one of them at first base and DH the other, that means Kenji or Clement is sitting. Somebody’s going to get the short end every day, there’s no way around it.

Riggleman said there still are no plans to play Johjima at first base, although he hinted that day might come.

“I can’t say it will never happen, but not right now,” he said.

Then there’s the issue of Sexson, who entered Monday’s game batting .220 with one extra-base hit since May 24. During the last homestand, the club discussed procedures for releasing Sexson.

Riggleman said he’s trying to be patient with Sexson, “waiting for him to get going. Richie’s got a lot of baseball left. Whether we can get it out of him or if he finds it here shortly, I don’t know.”

Rowland-Smith to start: With Felix Hernandez still gimpy with a sprained left ankle, the Mariners will dip into the bullpen and start left-hander Ryan Rowland-Smith tonight.

Riggleman said he would love to get five innings out of Rowland-Smith but knows he probably will be using the bullpen a lot. Rowland-Smith threw a season-high 53 pitches on June 18, when he worked 21/3 innings against the Marlins. His longest stint was 31/3 innings against the Nationals on June 13, when he threw 44 pitches.

“In my dreams, I can go five, six innings,” he said. “Realistically, they’ll probably hold me to 50 pitches or so.

“It’s not a big deal really, except to me. To me, getting a start is special, a chance to show what I can do in that role. Who knows, if I do well I may get another shot.”