noun
challenger
CHAL-in-jer/ˈtʃælɪndʒər/
Someone who contests another's position or claim.
The older challenger makes his move against the reigning chess champion.

Etymology
The verb behind challenger shifted from accusing people to calling them to fight. With the agent ending, it names the person issuing that call, including a competitor confronting a champion.
In context
it's our Challenger George Fazio 75 and still Champion that old tough guy from South Africa with a fine 69 Bobby Locke
More examples
- The challenger wins support in the final weeks of the campaign.
- Several challengers dispute the official account.
- The champion shakes hands with her next challenger.
Forms
challenger · challengers
Similar words
- contender
- Competes seriously for a title without necessarily opposing its current holder.
- opponent
- Anyone on the opposing side, including a defending champion.