SAN DIEGO (Reuters) - The San Diego Padres' grip on a National League playoff berth loosened further on Tuesday with a damaging 5-2 loss to the Chicago Cubs.

San Diego held a 6 1/2-game lead in the NL West a little over a month ago but their third straight defeat left the Padres (87-70) two games behind the division-leading San Francisco Giants (89-68) with five contests remaining.

Both the Braves and Giants were winners on Tuesday as the Padres failed to keep pace.

"Here's the deal. We know where we are," a defiant Padres manager Bud Black told reporters. "We have to get the bats going. Hopefully, we'll break out (Wednesday)."

Mat Latos lost his fourth straight start after allowing four runs in 5 2/3 innings and the Padres managed just four hits against Chicago pitcher Ryan Dempster in dropping 1 games behind the Atlanta Braves (89-69) in the Wild Card race.

Dempster struck out nine batters while Alfonso Soriano blasted two home runs to lead the Cubs.

Soriano's two-run blast off of Latos in the sixth put the visitors 4-2 up and he added a solo shot in the eighth.

Two errors by San Diego allowed the Cubs to take a 2-0 lead in the fifth before Nick Hundley responded with a two-run homer in the bottom half of the inning to tie the game 2-2.

However, Latos was unable to keep the home team on level terms as his late-season slump continued.

Earlier this season, the right-hander set a Major League record with 15 straight starts of five or more innings with two or fewer runs allowed but like his team, he has struggled since the All Star break.

After two more games against Chicago (72-85), San Diego will close the regular season with a pivotal three-game series in San Francisco.

(Reporting by Jahmal Corner in Los Angeles; Editing by John O'Brien)