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8/10/2014 3:31 P.M. ET

Walker suffers setback, likely headed to DL

PITTSBURGH -- The Pirates' hopes of embarking on the most difficult phase of their schedule in growing strength took a major hit Sunday morning when Neil Walker showed up at PNC Park unable to play.

Encouraged with how he felt, Walker had pinch-hit Saturday night and was penciled into Clint Hurdle's starting lineup for the series finale against San Diego. But the second baseman reported a setback in his condition, and now is likely headed for the disabled list.

"He didn't feel as good as he hoped to. We've reconfigured the lineup and he's not in it," Hurdle said. "We'll revisit what our next move will be after the game. We're coming to a crossroads here."

Walker has dealt with lower back tightness since last Saturday. He had returned to the lineup on Tuesday, but had to leave mid-game with renewed tightness.

His pinch-hitting appearance Saturday -- he was struck out by Joaquin Benoit leading off the ninth inning of the Bucs' 2-1 loss -- would add four days to a DL stint, which otherwise could have been backdated to Aug. 6.

Hurdle waved off that aspect of the situation.

"None of us has a crystal ball," Hurdle said. "It is what it is. To second guess or get disappointed because we did something we felt comfortable doing … No, not at all. We'll move on. It's kinda the way we're built."

With Andrew McCutchen also in recovery mode from an avulsion rib fracture, the Pirates on Monday will kick off a series against Detroit in which they will confront a quartet of pitchers with 44 wins among them. That will be the start of a month-long schedule against fellow contenders.

Martin not thinking about impending free agency

PITTSBURGH -- Russell Martin had a pretty short checklist when he showed up in Pittsburgh 21 months ago, and both items have been covered.

Help lead the Pirates back into the winner's circle? Check.

Re-establish my market value? Check.

Martin was refreshingly candid in November 2012, when he left the marquee Yankees to sign a two-year, $17 million contract with the Bucs, the richest they have ever given a free agent.

"I didn't want a long-term contract, especially coming off the season I had," Martin said at the time, when he was coming off hitting a career-low .211. "I feel I can play much better, improve myself, and go at [free agency] again in a couple of years."

That free agency is a couple of months away, and Martin, 31, is approaching it as a .290 hitter, and with his defensive reputation as gilded as ever.

There is a growing groundswell for the Pirates to re-sign him -- even though back in Spring Training manager Clint Hurdle all but anointed Tony Sanchez as his 2015 starter, and despite the likelihood that Martin has played himself out of the club's budget.

The catcher himself has not given this any thought yet.

"I'm here to play baseball," Martin said. "One game and one day at a time. And I kinda enjoy the process … Getting to that [free agent] status and seeing where it goes.

"I do absolutely love it here. I couldn't have made a better decision. I'm in a good place. We're in a good place."

Pirates add Minor League infielder Field off waivers

PITTSBURGH -- The Pirates claimed infielder Tommy Field off waivers from the Angels on Sunday. He was assigned to Triple-A Indianapolis.

Field, 27, has spent parts of three separate seasons in the Majors with the Rockies and the Angels, but he has spent all of 2014 with Triple-A Salt Lake, where he's hit .285/.351/.440 in 80 games.

With the versatility to play third base, second base and shortstop, Field has appeared in 33 career games in the bigs, collecting 17 hits in 76 at-bats (.224 average), all of which were singles. Field played in 15 games for the Angels last season, often appearing as a defensive substitute.

This is the second move for infield help the Pirates have made in the last week, as they also signed utility man Jayson Nix last Sunday. With Neil Walker dealing with nagging back issues, which could force him to the disabled list, Nix and Michael Martinez have been splitting time at second base.

Worth noting

• McCutchen lengthened his throwing to approximately 120 feet prior to Sunday's game as he continued to "add to and ramp up," per Hurdle, his rehab workouts.

General manager Neal Huntington, calling McCutchen's recovery process "fascinating," said the DL is not a consideration for him because it will be a net gain if he returns to play earlier than the 15-day DL period.

First number, last word

6-7: Pirates' record in Interleague play, entering a four-game set with Detroit beginning Monday night at PNC Park.

"Every team is dealing with injuries at this point of the season. It's survival of the fittest." - Huntington, on entering a challenging part of the schedule with McCutchen and Walker injured and Pedro Alvarez in reboot mode.

Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Stephen Pianovich is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.