SEATTLE -- Outfielder Michael Saunders was out of the lineup for the ninth time in the past 10 games on Monday as the Mariners opened a three-game series with the Red Sox as he continues working his way back from a strained right groin muscle.

Saunders tried to return on Friday against the Angels, but he felt the muscle tighten when he chased a line drive down the right-field line and came out after the fourth inning. Saunders did some pregame work Monday and manager Eric Wedge said it was up in the air whether he'd be available for pinch-hitting duties.

"He's getting a little better every day, so we'll see how he feels after he has some more activity," Wedge said. "I just want to work it to the point where when we get him in there next time, we can keep him there."

Saunders has been taking batting practice regularly and doing agility work, but he needs to be able to handle the quick burst required in the field before he can return to the outfield.

"It's more breaking and stopping like we saw on that ball down the line the other day," said Wedge. "It's just there when he really gets after it."

Montero's hard work paying off with power surge

SEATTLE -- Jesus Montero moved into a tie with Kyle Seager for the Mariners' home run lead on Sunday with his 15th of the season and is challenging to become the first rookie to lead the club in long balls since first baseman Alvin Davis in 1984.

With a month left in the season, Montero already is tied for the sixth-most home runs by a Mariners rookie, though well shy of Davis' club record of 27.

Interestingly, three of Montero's mashes have come against the Angels' Jered Weaver, one of the toughest right-handers in the American League.

Montero hit two home runs against Weaver in their first meeting this season last month in Anaheim when Seattle handed the three-time All-Star just his second loss of the season, then went deep again Sunday in the Mariners' 2-1 win.

Montero also hit a home run against Weaver last year while with the Yankees and is now 5-for-9 with four home runs in three games against him.

The only players with more home runs against Weaver in their careers are the Yankees' Alex Rodriguez (five in 24 at-bats) and Curtis Granderson (five in 25 at-bats). Two other players are tied with Montero with four home runs -- Raul Ibanez in 30 at-bats and Hank Blalock in 33 at-bats.

Both times Montero faced Weaver this year, he said he just tried to stay up the middle against Weaver's somewhat funky delivery.

"He throws across his body," Montero said. "He's tough. He's got good pitches. I just got lucky, I think."

What makes it all the more interesting is Montero normally hits left-handers (.324/.372/.527) much better than righties (.230/.263/.355). But manager Eric Wedge said he's seen improvement in that regard.

"He's been working in batting practice to be a little more consistent in his approach, and I think that's helped him see the ball better and lay off breaking balls a little better from right-handers," Wedge said. "When he does that, it gives him a better opportunity to get a better pitch to hit, and I think that's what you've seen.

"He's still young. It's his first full year in the big leagues. He's 22, so he'll continue to have some trials, but recognizing the ball and seeing the ball and not being in a hurry, all that pays off for you."

Kinney taking on bigger role in bullpen

SEATTLE -- Right-hander Josh Kinney has gone from a temporary midseason addition to a valued late-inning reliever over the past two months, highlighted again by Sunday's critical situation when he retired Mike Trout and Torii Hunter after starter Hisashi Iwakuma allowed two runners in the eighth inning of the 2-1 win.

Kinney, 33, pitched the first three months of the season with Triple-A Tacoma and threw just one-third of an inning in one appearance in his first seven games with the Mariners. Manager Eric Wedge gradually began working the veteran into more situations, and now that Brandon League and Steve Delabar have been traded, he's inherited even a larger role.

"Josh has some experience and has some big-game experience," Wedge said. "This is a guy that's just worked so hard from Spring Training on. We had a good conversation at the end of Spring Training. He went down there to Triple-A and really went right after what we talked about, and he deserves to be up here.

"Now he's pitching more meaningful innings for us. He's handled left-handers OK and he's done a real nice job."

Though Kinney pitched a pair of World Series games for St. Louis in 2006, he appeared in only 21 games that season as a similar midseason addition. After undergoing Tommy John surgery in 2008 and eventually joining the White Sox last year, he'd never again pitched that many Major League games in a season until now.

His 21 appearances for the Mariners going into Monday's action equaled his career high, and he's posted a 3.98 ERA in 20 1/3 innings.

Worth noting

• Reliever Shawn Kelley, who was hit in the elbow by a line drive in his last outing in Triple-A Tacoma, wasn't quite ready to return as planned over the weekend. Wedge said the hope was to get him in Tacoma's season finale Monday in Fresno.

• Kelley and Mike Carp, who is on an injury rehab with Tacoma, are among the players expected to be added as September callups on Tuesday once the Rainiers' season is over. Wedge wasn't giving any hints on Monday as to who or how many players would join Erasmo Ramirez and Carlos Peguero, who came up on Saturday.

"I'm not going to give a number yet, because we haven't talked to those guys yet," Wedge said prior to Monday's game. "I want to make sure they get through their game and take care of what they need to take care of, but we'll add a couple."

• The Mariners played their third consecutive day game on Monday, the first time the club has hosted three straight afternoon games since Sept. 4-6, 1999.

• Wednesday's game against the Red Sox is a 7:10 p.m. PT start, which is a change from the 12:40 p.m. time listed on pocket schedules printed before the change was made.