decathlon

biathlon, heptathlon, pentathlon, triathlon

bout, competition, contest, event, game, match, matchup, meet, sweepstakes (also sweep-stake), tournament, tourney

athletics, sport

battle, conflict, scrimmage, skirmish, struggle, tug-of-war, tussle

championship, national(s)

final, nightcap, play-off, semifinal

derby, field day, gymkhana, open, outing

marathon, race, ultramarathon

heat, round, run, set

rally, volley

round-robin, rubber, runoff, sudden death

dead heat, photo finish, seesaw

classic