It's an article of faith that the San Diego Padres normally will prevail in tight games because they have one of the top bullpens in the majors.

Conversely, the Pittsburgh Pirates are four games under .500 and a long shot to make the National League playoffs because their bullpen has failed them more often than not.

But if you're looking for a reason why Pittsburgh could polish off a three-game sweep of host San Diego on Wednesday afternoon, the bullpen is as good a place to start as any.

The Pirates went as all-in as they ever do at the trade deadline this month, adding veterans Kirby Yates and Camilo Doval to reliable holdovers such as Mason Montgomery and Gregory Soto. And in this series, the Pittsburgh bullpen has outdone the Padres'.

After allowing just one run in the last six innings of Monday night's 3-2, 12-inning victory, Pirates relievers backed Paul Skenes' six shutout innings Tuesday evening with three hitless frames. That netted Soto the win when Oneil Cruz launched a two-out solo shot off Padres star Mason Miller in the top of the ninth for the night's only run.

"I like how we attacked the strike zone after Paul left," Pittsburgh manager Don Kelly said. "They have a really good bullpen over there, but the fight our guys have showed to bounce back against a really good team ... our bullpen has been pitching really well."

Right-hander Bubba Chandler (6-8, 4.38 ERA) will start for the Pirates in the series finale. He's coming off a no-decision Friday in his team's 5-4, 10-inning loss at the Los Angeles Dodgers. Chandler permitted four runs and four hits over four innings, walking two and fanning six in an 88-pitch outing.

In his only career outing against San Diego, Chandler absorbed a 5-0 loss on April 6, yielding three runs and five hits in 4 1/3 innings while walking four and whiffing four.

On Wednesday he'll oppose Padres right-hander Randy Vasquez (9-6, 4.19 ERA), who last worked Friday in a 6-2 win over Minnesota. Vasquez allowed just two hits and two runs in seven innings, walking none and striking out three. He's 0-0 with a 4.70 ERA in four career outings against Pittsburgh.

The Padres entered this series on their best roll of the year, winning 21 of 28 games and taking a two-game lead over Arizona for the National League's last wild-card spot. But that lead is down to a game after the Diamondbacks rallied to beat the Chicago Cubs 5-4 on Tuesday night.

For San Diego, a lack of offense -- the team's primary bane over the season's first half -- has reappeared in this series. The Padres have just two runs over 21 innings and consistently have failed to produce a timely hit.

"We've faced a lot of tough pitching the last couple of days, and we haven't been able to come through," manager Craig Stammen said. "We have to take advantage of opportunities in games like this. Hopefully, we can do it tomorrow."

San Diego went 0-for-7 with runners in scoring position Tuesday and has just one hit in 20 at-bats in that situation during the series.