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8/4/2013 6:32 P.M. ET

Pennington's left foot sore after plunking

BOSTON -- Shortstop Cliff Pennington was out of the lineup Sunday, one day after being hit on his left foot by a pitch.

Pennington was hit on the side of his left foot by a Craig Breslow pitch in the eighth inning. Pennington was able to remain in the game, but his foot stiffened overnight.

Pennington said Sunday morning that he thought he was able to play, but manager Kirk Gibson has alternated playing Pennington and Didi Gregorius at short for the last few weeks.

The D-backs planned to send Pennington for an X-ray on Sunday.

"He's pretty sore," Gibson said.

Needing roster spot, Sipp optioned to Triple-A Reno

BOSTON -- The D-backs optioned left-handed reliever Tony Sipp to Triple-A Reno on Sunday to make room on the roster for starter Brandon McCarthy.

Sipp was supposed to be the team's left-handed specialist, but he has actually proven to be more effective against right-handed hitters, holding them to a .210 mark while lefties have hit .250 against him.

The D-backs acquired left-hander Joe Thatcher just prior to Wednesday's non-waiver Trade Deadline, and he now fills the left-handed specialist role.

"I think we view Thatcher as a better alternative as a left-handed guy," manager Kirk Gibson said.

Sipp was 3-1 with a 3.86 ERA, but the biggest concern was the fact that he walked 18 in 32 2/3 innings.

"If I feel sorry for myself, obviously it's going to have a negative effect on me," Sipp said. "The positive thing is right now ... I'm starting to feel like my old self, throwing strikes again. I feel like my stuff is better or getting better. Just have to continue to get better and take those steps towards the right direction."

Snake bites

• The D-backs will start Wade Miley and Randall Delgado against the Rays on Tuesday and Wednesday. After Thursday's off-day, the club is undecided about what to do with its rotation.

Arizona could give each of its starters and extra day of rest and have Zeke Spruill start again, or it could skip Spruill's spot.

• Gibson laid out what he thinks the D-backs have to do if they are to catch the Dodgers in the National League West race.

"For us, we need to stay focused on us," he said. "We just have to play good baseball and make the right play and keep trying to find the right combination so we play better. We still have a great opportunity going. It's not over, there's a long way to go, a lot can happen. We need to worry about ourselves, try and stay healthy, get our guys playing well, find the right lineup, find the right combination, rotation set properly and make good decisions with our bullpen. And you've got to believe just like you did at the beginning of the season that you can be where you want to be at the end of the year."

• Entering play Sunday, the Dodgers had won 13 straight road games.

"Are they going to stay that hot all year?" Gibson said. "Well, I hope not, because if they do, we aren't going to catch them -- let's be honest. We just have to play more consistent ourselves. We've got to start winning series and sweeping some series. We've got a tough schedule ahead of us."

• Wil Nieves made his first career start at designated hitter on Sunday.

Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.