PITTSBURGH -- Brian Burres, not Jeff Karstens, will now start the Pirates' series opener against Atlanta on Monday, as right shoulder soreness has sidelined Karstens once again.

Karstens had returned to the mound last Tuesday and pitched well in the team's win over Chicago. However, during his bullpen session late in the week, Karstens once again felt the same arm discomfort that had caused him to miss a start less than two weeks earlier.

The Pirates are not ruling out Karstens' ability to return before the end of the season. But it's not guaranteed that he will, either. That determination will be made once the Pirates see how Karstens' shoulder responds to rest and treatment.

Karstens did have his shoulder examined and no structural damage was found.

"It just doesn't feel right," manager John Russell said. "It's been a long year for him, and it's a little cranky."

The Pirates were already going to be cautious with how much Karstens pitched during this last month given that he has thrown more innings (121 1/3) than in any year since 2006. And as general manager Neal Huntington noted on Sunday, the fear that Karstens might wear down at the end of the season was one of the reasons why the organization initially saw the right-hander as fitting best in the bullpen.

"He's not the most physical guy," Huntington said. "He doesn't do it the easiest. But I'll tell you what, he's given us everything he's had every time he goes out. He's shown us that there is definitive value. He's shown us that Jeff Karstens can get Major League hitters out. For many periods this year, he was our most consistent starter."

Though Karstens' future with the organization might not be as a starter, he came up big for the Pirates in that role on a number of occasions this year. Thrust into the rotation at the end of April, Karstens became a permanent part of it beginning in June. He posted a 4.88 ERA in 25 games (19 starts) after not beginning the season on Pittsburgh's 40-man roster.

Walker reaching Pirates' rookie milestones

PITTSBURGH -- Neil Walker's fifth-inning double in Saturday's loss not only extended his hitting streak to 11 games, but it put the second baseman in select Pittsburgh company.

The hit was Walker's 100th this year, making him just the sixth Pirates switch-hitter to reach the 100-hit plateau as a rookie. The feat hadn't previously been done since 1982, when Johnny Ray knocked 182 hits as a rookie. The rest of Walker's company includes Jim Russell (138 in '43), Johnny Gooch (116 in '22), Max Carey (110 in '11) and Otis Clymer (108 in '05).

With just less than a month's worth of games remaining, Walker seems to have a good chance to move up to at least third on that list. After collecting three more hits in Sunday's 8-1 loss, Walker now enjoys a 12-game hitting streak. No Pirates player has had a longer such streak this season.

In this 12-game span, Walker has gone 22-for-53 with 14 RBIs and 11 runs scored. Half of his hits have gone for extra bases.

Walker won't be the only Pirates rookie to collect 100 hits this season, as Jose Tabata sat just five hits shy of the mark heading into Monday's series opener against the Braves. The Pirates haven't had a pair of rookies record 100 hits in the same season since 1997, when Jose Guillen (133) and Tony Womack (178) did so.

Martinez called up to help out bullpen

PITTSBURGH -- Wanting an additional option out of the bullpen, the Pirates recalled right-hander Joe Martinez from Triple-A Indianapolis on Sunday. Martinez is the second player called up by Pittsburgh since rosters expanded on Wednesday.

Though Martinez has been pitching in Indianapolis' rotation since shortly after being acquired from the Giants on July 31, he will not be used as a starter unless other injuries dictate the need to have him make an emergency start.

"He has had some success, but has had some struggles here and there," manager John Russell said. "He's a kind of guy that we look at as a starter candidate down the road. He's a guy that can give you some depth."

In seven games (four starts) with Indianapolis, Martinez allowed 18 earned runs in 28 1/3 innings. He struck out 18 and walked seven. Overall this season, Martinez went 6-5 with a 3.94 ERA in 21 Triple-A games.

The Pirates wasted no time getting Martinez involved, as Russell called on him to pitch three innings in Sunday's 8-1 loss to Washington. Martinez allowed three hits and two unearned runs in the appearance.

When he took the mound, Martinez became the 47th different player used by the club this season. The franchise record is 49, set in 1987 and matched in '01. The Pirates have used 26 different pitchers, which matched the club high set two years ago.

Huntington to bring up reinforcements

PITTSBURGH -- Though the team's roster already sits at 27 players, general manager Neal Huntington confirmed that the Pirates have more September callups on the horizon. Those additional summonses will come on Tuesday, after Triple-A Indianapolis completes its season.

Among those being considered for a callup is right-hander Brad Lincoln. Lincoln will make his final start for Indianapolis on Monday, and management hopes that it goes better than Lincoln's return from neck soreness last Wednesday.

Lincoln could fill Jeff Karstens' spot in the rotation if Karstens isn't able to return before the end of the year. The Pirates have also toyed with the idea of going with a six-man rotation this month. However, Lincoln has to prove, first, that he deserves even being called up.

"It depends on where Brad is and how he feels and what type of command he has," Huntington said. "I don't want to make [Monday's start] a do-or-die situation for Brad. It's going to be dictated by his health, and then also the command of the stuff that he has coming out."

Even if Lincoln does not join the big league club, Huntington said other players will. Recent injuries to Ross Ohlendorf, Karstens and Jeff Clement will force the Pirates to bring up more players than initially anticipated.

The Pirates probably will add a third catcher to the roster. Left-handed reliever Justin Thomas is another likely callup given that he is already on the 40-man roster.

Two players whose numbers appear to warrant callups -- Brandon Moss and Alex Presley -- could be squeezed out of the chance for two reasons. Neither is currently on the 40-man roster, and the Pirates don't have much outfield playing time available.

Moss' situation is especially interesting, given that he has had a rebound season after being demoted. If the Pirates don't add Moss to the 40-man roster this offseason, he will become a Minor League free agent.

"Brandon is the one that emotionally you would love to bring to the big leagues," Huntington said. "Intellectually, you take a step back and how does he fit short term? How does he fit long term? How does he get an opportunity to show us what he's done? Because there are some other guys that are going to continue to play."

Worth noting

General manager Neal Huntington said that the organization will wait until after the Minor League season to decide which three pitchers the organization will send to the Arizona Fall League. By waiting that long, the development staff will know which pitchers could use extra innings and which might benefit ending their seasons now. ... Right-hander Craig Hansen has been promoted to Double-A Altoona. Hansen allowed six earned runs, 13 hits and 11 walks in 14 innings with Class A Advanced Bradenton after missing more than a year with a nerve issue in his neck. ... Bradenton has its first game in the Florida State League playoffs on Tuesday against the Charlotte Stone Crabs. The Marauders clinched the South Division title with a win on Saturday.