Refers to the leading unit in a military advance or, by extension, the forefront of a movement or field.
彼の部隊は先鋒として敵陣に突入した。
His unit charged into the enemy camp as the advance guard.
その会社は業界の先鋒として新技術を導入した。
The company introduced new technology as a vanguard of the industry.
first competitor in a team match
Used in sports like kendo and judo for the athlete who competes in the opening bout of a team competition.
先鋒の選手が一本を取って、チームに勢いをつけた。
The first competitor scored an ippon and gave momentum to the team.
先鋒 is a somewhat literary term for the one who takes the initiative or leads an attack, while 一番手 is a more neutral, everyday word for the first person to act.
先鋒 names the frontmost fighter or spearhead of a group action, close to 先駆け's second sense of leading an attack.
In team martial arts, 先鋒 is the first competitor to fight while 大将 is the last, usually the team's strongest member.
先鋒 is the vanguard or lead unit in an advance, the military opposite of 殿（しんがり）, the rear guard.
vanguard; forefront; leading figure
A Sino-Japanese word inherited from Chinese 先鋒, combining 先, “foremost,” and 鋒, “weapon point” or “spearhead.” It originally denoted the foremost attacking force and later the first competitor in a team match.