Sexson hit his fourth grand slam of the season in the 10th inning to give Seattle a 5-1 victory over the Tampa Bay Devil Rays on Tuesday night.
"You're going to get fired up in that situation, but the whole purpose is to stay as non-emotional as you can so you can focus. Don't get wild up there," Pentland said. "It's like a shark. He just eats you and doesn't feel sorry for you. He just goes about his business. That's the approach you need to take to the plate."
Sexson has been taking that approach, particularly after opposing teams walk Raul Ibanez in front of him.
Ibanez has been intentionally walked 14 times this season. Sexson has followed with eight hits in 12 at-bats, including three homers, and a pair of walks. His four slams this season tie the club record set by Edgar Martinez in 2000.
"That's what Pentland calls `a shark mentality.' A shark doesn't get emotional. You have to try to maintain your emotions," Ibanez said. "It seems like every time, Richie does that."
After Devil Rays manager Joe Maddon ordered Beltre and Ibanez walked, Sexson cleared the bases with a drive to center field. It was his 25th home run this season and 13th career slam.
"That's a great situation to be in," Sexson said. "I love those situations when a fly ball does it. They have to come into your zone there. A fly ball wins the game."
Maddon and McClung believed they had a plan to get through the at-bat. McClung started Sexson out with an outside slider. The intention was to have him looking away, then bust him inside with a fastball.
"The pitch was executed," McClung said. "It was just that Richie Sexson executed it, too. He was just focused on getting something in and he got it. I was hoping his bat would be a little slow and he would hit something on the ground. We made a plan and it didn't work."
Mariners manager Mike Hargrove added: "The whole idea when you put a lineup together is to make the other manager pick his poison. Richie has come through like that on a number of occasions this year."
Julio Mateo (8-4), who worked 1 1/3 scoreless innings, earned his second win in two nights. Mateo is tied with Atlanta's Oscar Villarreal for the most wins among relievers.
Both starters were efficient and effective. Tampa Bay's Jae Seo went seven-plus innings, allowing five hits with one walk and five strikeouts. He threw 93 pitches.
Mariners right-hander Felix Hernandez allowed five hits and a run in eight innings with five strikeouts.
"It was a good game on both sides," Hernandez said after his longest outing since June 11. "I was really proud of it."
Seo contained the Mariners on just four hits and no runs through six innings, but he and catcher Dioner Navarro gave up a gift run.
Seo struck out Ben Broussard to open the seventh, but his third strike was wild and in the dirt. Navarro, who came with Seo to Tampa Bay in a five-player trade with the Los Angeles Dodgers, allowed the ball to escape up the third-base line far enough that Broussard reached first.
Broussard kept going and raced to second on Navarro's throwing error. Kenji Johjima followed with an RBI single down the left-field line to tie it at 1.
The Devil Rays scored in the third on what might have been a fortunate mistake.
Russell Branyan opened with a single and Ben Zobrist walked. Despite a swing and miss by Rocco Baldelli on an apparent hit-and-run, both runners converted a double steal. They were the season's first stolen bases for both runners. Baldelli followed with a groundout, scoring Branyan.
The Mariners won for just the fourth time in 11 extra-inning games.
- The Devil Rays are 8-19 since the All-Star break and 18-25 in Seattle, having lost six of their last seven games at Safeco Field. Their 18-41 road record is the second-worst in the AL.
- Branyan's hit in the third inning was his 11th single this season. That matches his home run total.