double riichi; declaring riichi on the first discard with no tile calls
Mahjong term: a special riichi declaration made on the very first turn before any tiles have been called, ponned, or kanged. It is worth extra points.
See also: リーチ
Double riichi can combine with ippatsu.
being one step away from victory with two possible paths
Figurative use derived from mahjong: describes a situation where success is close and there are two distinct ways to achieve it. Often used in sports, business, or competitive contexts.
The dealer's double riichi quickly widened the point gap.
One more win to the championship, and both upcoming opponents are lower-ranked — it's exactly a double riichi situation.
From mahjong terminology: ダブル (double) + 立直 (riichi, a declaration of being one tile away from winning). The figurative sense extends the idea of having two immediate paths to victory.