Possible Clues:

• Defeated rival
• Beck's first smash
• The hare, to the tortoise
• Member of defeated team -- not keeper, proverbially
• Sore sort, maybe
• Last place finisher, obviously
• Runner-up maybe less tense after conceding round
• Olympian who doesn't medal
• One not getting an Olympic medal
• “Soy un perdedor, / I’m a ____ baby, so why don’t you kill me?” (Beck)