D.C. United improved to 9-4-3 and moved four points ahead of the New York Red Bulls for first place in the Eastern Conference. It's their first four-game winning streak since the 2008 season.
The struggling Union (2-8-2) saw their winless skid reach six. They haven't won since a 1-0 victory over Chivas USA on April 21.
A sellout crowd of 18,876 showed up at PPL Park for the debut of interim manager John Hackworth, who was elevated when Peter Nowak stepped down on Wednesday after two-plus seasons.
Hackworth was an assistant coach under Nowak since the Union's inception in 2010.
But the Union sputtered again offensively and couldn't add to their season total of eight goals. That production is tied with Toronto FC for last in the 19-team league.
D.C. United leads the league with 29 goals.
(Copyright 2011 Philadelphia Union. Reprinted by permission)