BOYDS, Md. - Antoine Hoppenot scored in extra time Tuesday night to give the Philadelphia Union a 2-1 win over D.C. United in a battle of MLS teams in the fourth round of the U.S. Open Cup.

The win gave Union a berth in the quarterfinals.

They will host the Harrisburg City Islanders of the third-tier United Soccer League on June 26.

The Islanders upset MLS' New York Red Bulls on Tuesday.

Brian Carroll scored in first-half injury time for the Union. Josh Wolff netted for United, also in first-half injury time.

Hoppenot's goal came with an assist from Freddy Adu early in the first extra period.