McCollum 's shot capped a final minute in which the two teams traded leads six times .
Dirk Nowitzki hit two clutch three - pointers , the second a potential game - winner with 3.9 seconds left .
McCollum 's shot capped a final minute in which the two teams traded leads six times and Dirk Nowitzki hit two clutch three - pointers , the second a potential game - winner with 3.9 seconds left .