It was an up-and-down June for the AL West-leading Texas Rangers.

It was mostly down for right-hander Justin Grimm, who's hoping another start against the Seattle Mariners in Tuesday's series opener will help him and his club get off to a better start in July.

Texas (48-34) entered June three games up on Oakland for the West lead, but lost 12 of 17 to fall three back of the top spot. The Rangers, though, finished the month with a half-game division lead over the Athletics after winning for the ninth time in 11 games Sunday, 3-2 over Cincinnati.

"It's the best .500 month ever - to go from where we were and the stretch we knew we had in front of us," closer Joe Nathan told the Rangers' official website. "... Guys knew not to give up and keep pressing on."

Grimm (7-5, 5.56 ERA) will try to do that after going 2-2 with a 9.00 ERA in five June starts. The rookie had the majors' worst ERA in that month of anyone to pitch at least 25 innings, and he's failed to make it through six in half of his 14 starts this season.

"I'm not happy being a five-and-dive guy," he said after allowing three runs over five innings in Wednesday's 8-5 win in the Bronx.

Grimm has gone at least six while winning his last two starts against the Mariners (35-47), giving up five total runs in 12 1-3 innings.

"It's Seattle. ... they've seen me here or there, but if I'm executing my pitches, I'll get them out," Grimm said.

Losers of nine of 13, the Mariners could use a quality start from Joe Saunders (5-8, 4.98) as they kick off their six-game trip. The left-hander, though, has a 9.91 ERA while losing all seven regular-season starts in Arlington after lasting 4 2-3 innings and yielding all the runs in 7-0 loss April 19.

Saunders won the 2012 AL wild-card game at Rangers Ballpark while with Baltimore, but no pitcher in the stadium's history has that many regular-season losses without a victory.

"You know it's going to be hot, you know it's going to be steamy, and you've just got to try to hydrate the best you can," he told the Mariners' official website. "... You've just got to go out there and execute your pitches."

That didn't happen last Tuesday when Saunders was charged with six runs and six hits - including three homers - in 1 2-3 innings of a 9-4 loss to Pittsburgh.

Saunders has surrendered four homers to Ian Kinsler - his most to anyone - but the second baseman is 0 for 6 in that matchup this season. Kinsler is hitless in his last 15 at-bats.

Leonys Martin, who has hit safely in 14 straight, went 3 for 7 as the Rangers outscored the Mariners 23-3 in their lone visit to Arlington this season from April 19-21.

Kyle Seager had six of the Mariners' 18 hits in that set and is batting .366 in the season series as Seattle has dropped seven of 10. Seager, 3 for 9 with two doubles off Grimm, has two hits - both homers - in 27 at-bats over the last six games.

With Dustin Ackley, Franklin Gutierrez and Michael Morse injured, the Mariners could use more power from Raul Ibanez, whose 10 homers in June matched a career high in a month.

It's uncertain if Lance Berkman will return after missing the Rangers' weekend series with a knee injury suffered when he stumbled down the stairs of the team's charter plane.