Thairo Estrada homered in the seventh, Wilmer Flores connected in the eighth and the San Francisco Giants held on to beat the Chicago Cubs 4-2 on Sunday night. The Giants kept the Cubs' offense in check while using six pitchers on a bullpen day, though Zach McKinstry had four hits for the Cubs, who have dropped 15 of 21. Estrada, Evan Longoria and Austin Dean had two hits each for the Giants, who had lost five of six.