Sept 24 (Reuters) - U.S. stock indexes opened lower on Friday following a strong two-day rally, as worries persisted about the spillover from debt-laden China Evergrande, while Nike tumbled after cutting its sales forecast. The Dow Jones Industrial Average (.DJI) fell 2.51 points, or 0.01%, at the open to 34,762.31. The S&P 500 (.SPX) opened lower by 10.94 points, or 0.25%, at 4,438.04, while the Nasdaq Composite (.IXIC) dropped 90.63 points, or 0.60%, to 14,961.62 at the opening bell.