Alfonso Soriano hit a go-ahead homer in the eighth inning and the Cubs snapped an eight-game losing streak with a 5-3 win over the slumping Cincinnati Reds on a rain-soaked Thursday night.With the score tied at 3, Reds reliever Sean Marshall (4-4) walked Anthony Rizzo. Just as the skies cleared up, Soriano cracked a two-run shot to center field off Logan Ondrusek.Shawn Camp (3-5) pitched a perfect eighth for the win and Carlos Marmol worked the ninth for his 14th save in 16 chances.Todd Frazier and Zack Cozart homered for Cincinnati after the start was delayed by rain for 1 hour, 20 minutes. The NL Central leaders lost their fifth straight but remained 2 1/2 games ahead of second-place Pittsburgh.