ARLINGTON, Texas -- The Texas Rangers took over first place in the American League West on Sunday, and they can thank their first offensive explosion of the season.
Nelson Cruz's grand slam capped a five-run fifth inning, and the Rangers completed a three-game sweep of the Seattle Mariners with an 11-3 victory at Rangers Ballpark.
"I think this series was an indication of what our offense is capable of," said first baseman Mitch Moreland, who hit one of four Texas home runs. "I don't think we're close to where we could be, but we put a step forward for sure with the runs we put up today."
With the Rangers sweeping the Mariners while the Oakland A's lost three straight in Tampa Bay against the Rays, Texas took a half-game lead in the division.
The Rangers' run total was a season high, surpassing the previous high of seven.
Cruz's 431-foot grand slam off Mariners starter Aaron Harang, the fifth of his career, boosted Texas' lead to 8-2.
"It looked like the first couple of innings we were trying to figure Harang out," Rangers manager Ron Washington said. "The pitch count started to rise, and he made some mistakes and we capitalized."
Adrian Beltre and Leonys Martin also homered for Texas, with Martin collecting the first of his big-league career. Texas sent runs across the plate in four consecutive innings spanning the third and sixth to overcome what was a 1-0 deficit.
Lost amid the offensive assault was the work of Rangers starter Justin Grimm (1-0), who finished with a career-high nine strikeouts. Grimm, making his sixth career start and second consecutive against the Mariners, allowed just one run on six hits and one walk in six innings.
"It all started with Grimm on the mound," Washington said. "He was able make good pitches at the right time. He kept the ball down and changed speeds and threw the ball the way we thought he was capable of throwing to give us a chance."
Cruz finished with two hits and two runs. Martin had a triple in addition to his home run.
"The offense did the job when we needed a clutch hit to get it done," Cruz said. "It feels pretty good."
Kyle Seager, who extended his hitting streak to 10 games, led Seattle with three hits and two RBIs. He hit a solo home run in the ninth inning.
Seager's RBI double in the first inning ended a streak of 19 consecutive scoreless innings for the Mariners, who were shut out the first two games of the series.
After Martin tied the game at 1 with his third-inning homer, Moreland pushed the Rangers to a 3-1 lead following a two-out single from Cruz. Moreland sent a 2-1 pitch deep to center for his third homer of the season.
"I got up here and missed a pitch early that I thought I could hit and tried to hang in there at that at-bat and got another one and put a pretty good swing on it," Moreland said.
Martin's hot bat continued in the fifth. Martin sent a leadoff hit down the right field line for a triple. Kinsler singled on a blooper to right, bringing Martin home. Texas loaded the bases for Cruz, who sent a 2-0 pitch sailing over the center field wall.
Beltre joined the long-ball party in the sixth with a two-run home run to left. Jeff Baker completed the offense for Texas with a pinch single to left, scoring Kinsler from second.
Harang (0-2) went 4 2/3 innings, giving up eight hits and eight runs. Blake Beavan followed, and he allowed three runs in 3 1/3 innings.
Rangers reliever Michael Kirkman threw three innings of one-run ball to pick up a save.
NOTES: Grimm's previous best in strikeouts was seven, set in his major league debut against the Houston Astros on June 16, 2012. ... Seattle batters struck out 31 times during the three games. ... Texas departs for a seven-day, seven-game road trip beginning Monday. The Rangers have three scheduled against the Los Angeles Angels before four against the Minnesota Twins. ... Seattle concludes a six-game road trip with three at Houston.