HARRISON, N.J. — Since 1996, the first year of Major League Soccer, D.C. United has been the guys in the black hats — actually the all-black uniforms — first against the MetroStars and now against the Red Bulls.

While D.C. has won four league titles, the Red Bulls have a trophy chest that is bare except for last season’s Supporters Shield as the No. 1 team over all during the regular season. And that did not mean much after the Red Bulls were ousted in the Eastern Conference semifinals by Houston.

On Sunday, before an announced crowd of 18,054 at Red Bull Arena, the home team shook off tired legs and, playing in its third game in eight days, cobbled together one of its strongest matches of the season. The Red Bulls, led by two sparkling assists by their captain, Thierry Henry, defeated D.C., 2-0, in the first leg of a home-and-home conference semifinal series, which will be decided by total goals. The return match will be played Saturday in Washington. A tie or a loss by one goal would send the Red Bulls to the next round.

For Henry, 37, the match again showed a player with exquisite skill, vision and determination.

“When No. 14 is in the mood, he simply can’t be stopped,” Red Bulls midfielder Dax McCarty said. “Today, he was as close to unstoppable as anyone in this league can be. No one knows his plans — maybe he does — and I think part of it is that he’s motivated to prove that he’s still a great player. He’s not only a great player but a great leader, a leader by example.”