noun
front runner; front-running horse
In horse racing, a horse that takes the lead early and tries to maintain it to the finish.
あの逃げ馬はスタートから先頭を走っている。
That front runner has been leading from the start.
今日のレースでは逃げ馬がそのまま逃げ切った。
In today's race, the front runner held on to win.
Compound of 逃げ (nige, 'escaping, running away') + 馬 (uma, 'horse'). The term is specific to horse racing.