With four days remaining until the non-waiver Trade Deadline on Sunday, National League general managers are working their phones in hopes of landing the piece or pieces to improve their team.

One area on almost every team's list is bullpen help, and while there are certainly relievers available, don't be surprised if sellers hold on to their players until the last possible moment to get the best return.

One thing each contender must do is weigh the outcome of any potential deal. That especially holds true for the D-backs and Pirates, who are in contention a bit later than many outsiders predicted, but also the Phillies and Giants, who must decide how much they're willing to give up for a two-month rental.

In the NL East, the Phils and Braves have used two of the league's best pitching staffs to build a solid lead over the rest of the division. Both teams seem to be on cruise control and are strong candidates to advance to the playoffs, but they are still likely looking to improve, with each club seeking to bolster already-solid bullpens for a World Series run.

Trade Include

How the tight NL Central race shakes out could very possibly be contingent on what moves occur before the Deadline. With the Brewers, Cardinals and Pirates all vying for the top spot in the division, whoever wins the Deadline dealings must be viewed as the favorite to win the Central. Milwaukee has already acquired Francisco Rodriguez and would seem to be the most aggressive, since this is most likely its last chance to win it all with free-agent-to-be Prince Fielder.

In the NL West, the Giants have a three-game lead over the D-backs and definitely need offense. How much Arizona (and Pittsburgh in the NL Central) can help its chances without giving up its future will be one of the most interesting themes as the Deadline nears.

Below are eight NL contenders and what they're looking for as the Deadline nears.

Phillies
65-37, six-game lead in NL East
Philadelphia would like to add a right-handed bat and relief pitcher before the Deadline, but the four-time defending division champs don't necessarily need to do so. The Phils need to improve against left-handed pitching, but that weakness certainly hasn't hampered them thus far.

Bullpen-wise, Brad Lidge has returned from the disabled list, but Jose Contreras hasn't yet started a throwing program. Even so, Lidge's return could end up being akin to a solid midseason acquisition.

Giants
59-44, three-game lead in NL West
Any offense will make the Giants happy. They're also not being picky and would like to upgrade anywhere they can.

"I think we need to upgrade. Whether that can happen in a significant way, I'm not sure. The talent pool isn't in our favor," general manager Brian Sabean said. "Having said that, I don't believe there's a silver bullet. Quite frankly, the lineup needs a lot of help. It might not be just one player."

Braves
60-44, six games behind in NL East, 3 1/2-game Wild Card lead
The Braves' big three of Eric O'Flaherty, Jonny Venters and Craig Kimbrel has been perhaps the best back end of any bullpen in the game.

Atlanta would still like to add another piece, though, preferably a right-hander. Like the Phillies, the Braves might have an in-house option in Peter Moylan, who could return in late August. Still, another relief weapon is never a bad thing in October.

D-backs
56-47, three games back in NL West, 3 1/2 games back in Wild Card
One would think Stephen Drew's season-ending injury would have Arizona looking for a replacement, but general manager Kevin Towers said that's not the case. The D-backs are still intent on adding pitching.

Starting pitching is thin, so while the D-backs would like to upgrade there, they might have to focus on the 'pen. Towers said one thing is clear, however -- they will not sell their future for a quick fix.

Brewers
55-49, one-half game back in NL Central, five games back in Wild Card
With K-Rod in hand, the Brewers now need to find some left-handed relief help. Mitch Stetter left a recent rehab outing after having issues with his left hip, while Zach Braddock was demoted to the Minors last week and is on the inactive list. Manny Parra is still on the DL with elbow issues and is unlikely to pitch again this season.

Milwaukee also looked at upgrading the left side of the infield, but Yuniesky Betancourt and Casey McGehee have played better as of late. Plus, there aren't many starting third basemen and shortstops available.

Cardinals
55-48, one-half game lead in NL Central, 4 1/2 games back in Wild Card
The Cards are yet another team looking to add a right-handed reliever. St. Louis is fine at the back end with closer Fernando Sales and Jason Motte, but needs depth after Eduardo Sanchez was shut down last week after experiencing shoulder discomfort during a rehab outing. Manager Tony La Russa is aware of his team's chances of landing a top reliever.

"If there's one guy you identify, I guarantee you there's a half-dozen clubs going after him," La Russa said last week.

Pirates
53-48, one game back in NL Central, 5 1/2 games back in Wild Card
The surprising Bucs want to improve their offense, but they're also not willing to mortgage their future, general manager Neal Huntington said.

"We're absolutely motivated to help this club," Huntington said Sunday. "We're just not motivated to do something stupid or foolish. This club deserves something to help them, but at this point, the acquisition costs are just so high that it's been a challenge."

Third baseman Pedro Alvarez could provide some offensive punch. He swung the bat well in Triple-A but has struggled in the Majors this season.

Reds
50-53, five games back in NL Central
The Reds seem to have the longest shot to make the playoffs, with three teams to leapfrog in their division. They already have the talent to make the NL Central race even more exciting, but general manager Walt Jocketty said last week he will peruse the market.