Complex sentence: Mercer's only chance to score came in the fourth; after Vandy had fumbled Mercer completed a pass down to the ten yard line, but that's where Mercer was still when the game ended.
Split into simpler sentences: Mercer's only chance to score came in the fourth quarter. After Vanderbilt had fumbled Mercer completed a pass down to the 10-yard line, but that's where Mercer was still when the game ended.