SAN DIEGO -- The way general manager Kevin Towers was sweating it over in mid-March, one would never imagine hearing the bullpen described as the glue of the 2009 Padres.

With only two weeks remaining in spring training, Towers and manager Bud Black were in a frenzied state trying to find the right mix of relievers to bridge the gap to new closer Heath Bell.

The team's top offseason acquisitions, Chris Britton and Mark Worrell, weren't the answer. And, at the time, few pitchers were standing out internally.

But following four shutout innings by the bullpen in the Padres' 4-3 victory in 10 innings over the Seattle Mariners on Thursday afternoon in front of 25,146 at Petco Park, first baseman Adrian Gonzalez was highly complimentary of the relievers. That effort by the bullpen, along with Kevin Kouzmanoff's two-out single in the 10th, gave the Padres their first win in interleague play since June 20, 2008, ending a major-league record streak of 13 straight losses against the American League. It also was the Padres' first win over Seattle at home since June 23, 2006.

"They've been awesome," said Gonzalez, who was 4-for-4 and blasted his major-league leading 23rd home run. "Even the guys they're sending down have been great. The bullpen has been probably the best part of our season so far, and they're the reason we're close to .500."

After Bell, the bullpen's makeup was dicey at best when the Padres optioned Britton to the minors and announced Worrell was having season-ending reconstructive elbow surgery.

The Padres brought in Duaner Sanchez off waivers and traded for Luke Gregerson, Frankie De La Cruz and Edward Mujica, all at little cost. They also claimed Rule 5 draft pick Luis Perdomo off waivers.

During the team's first 12 games, Padres relievers were stellar as the team opened with a stunning 9-3 start. Although an inexperience relief corps struggled over the next month, they began improving in mid-May when Sanchez was released and Edwin Moreno was sent to Triple-A Portland.

Since then, Padres relievers are 4-2 with 11 saves and a 2.47 ERA in 109 1/3 innings. Following six innings of three-run ball by starter Josh Geer on Thursday, the trio of Greg Burke, Mujica and Bell kept the game knotted at 3 after Gonzalez tied it with a solo blast to center in the sixth inning -- his first homer since June 2.

Burke, an undrafted rookie out of Duke, struck out two during a 1-2-3 inning that lowered his ERA to 1.65. Mujica followed with another scoreless inning to lower his ERA to 2.16. After pitching only once in the past week, Bell (3-1) pitched two scoreless frames to keep the team tied into the bottom of the 10th inning.

"The bullpen's turned it around," said Bell, noting that Sanchez's release and Moreno's demotion provided a wake-up call. "Everybody kind of realized we needed to step up our game and we kind of realized, especially the young guys, that if we're going to win games, it's going to be because of the bullpen."

With the offense struggling and two starting pitchers sidelined by injury, Black has leaned on his relievers to keep the team afloat. On Thursday, that meant going an extra frame until Kouzmanoff followed Gonzalez's two-out double to right-center with a blooper to left-center off Miguel Batista (3-2). It was the only hit in 16 at-bats for the Padres' five through eight hitters.

"We got the hit at the end," Black said. "We had the chance a couple of times to get the hit and finally we did. But it's good any time to get the 'W.' "