Chicago Cubs (48-34, first in the NL Central) vs. Houston Astros (49-33, first in the AL West) Houston; Saturday, 7:15 p.m. EDT PITCHING PROBABLES: Cubs: Colin Rea (4-3, 4.42 ERA, 1.39 WHIP, 54 strikeouts); Astros: Lance McCullers (0-0) Astros -126, Cubs +105; over/under is 8 1/2 runs BOTTOM LINE: The Houston Astros will try to keep their nine-game home win streak alive when they take on the Chicago Cubs. Houston is 49-33 overall and 31-13 at home. Astros pitchers have a collective 3.42 ERA, which ranks fourth in the majors. Chicago is 48-34 overall and 23-19 in road games. The Cubs have the third-ranked team slugging percentage in the NL at .444. The teams square off Saturday for the second