PREVIEW: Cubs at Pirates PITTSBURGH (Interstat) — The Chicago Cubs and Pittsburgh Pirates open a three-game series Friday at PNC Park, with the first pitch set for 7:05 p.m. under clear skies and 76-degree temperatures. Right-hander Colin Rea (0-1, 7.20 ERA in his past two starts) is expected to take the mound for the Cubs, while right-hander Mitch Keller (1-3, 4.50 ERA over his last four outings) is the probable starter for the Pirates. Rea enters on a two-start losing streak, having allowed four earned runs in five innings in a 5-1 loss to Detroit on July 22, and three earned runs in six innings in a 5-2 loss to Minnesota on July 17. He did, however, earn wins in his two prior starts, including a 9-7 victory at Baltimore on July 8 and a 23-3 rout of San Diego on July 1. Keller is coming off his best outing of the month: five scoreless innings with six strikeouts in a 5-3 win at the New York Yankees on July 22. That performance followed a rocky pair of starts (Interstat) — a 5-10 loss to Atlanta (three innings, three earned runs) on July 9 and a 5-9 loss at Washington (six innings, five earned runs) on July 3. The Cubs (57-45) hold a 12-game cushion above .500 and sit near the top of the National League Central. They split a four-game series with the Pirates in Pittsburgh from May 25-28, taking the first two (7-2, 10-4) before dropping the final two (1-12, 1-2). In the season series overall, Chicago has won four of seven meetings. The Pirates (52-51) are just one game above .500 and have lost three straight, most recently a 2-0, 10-inning defeat Wednesday at the Yankees. That game saw Keller’s strong start overshadowed by a bullpen collapse and a lack of run support. Despite the Cubs being installed as a 1.5-run favorite, Interstat’s game simulator projects a 6-5 Pirates victory. The over/under is set at 7.5 runs. Both teams are coming off off-days Thursday. The Cubs’ next 10 games include a four-game set at St. Louis and a home series against the Yankees. The Pirates will host Arizona after this series, then travel to Cincinnati and Milwaukee.