Newly acquired Brandon McDonald and Dwayne De Rosario are both eligible for this match for D.C., and could each start.
The Union ended a 294-minute goal drought last week in its 3-2 home victory against Chivas USA.
Danny Mwanga scored his fifth goal in that Union victory, and now leads the team in that category.
The Union have taken over first place in the Eastern Conference with a 7-4-5 record.
D.C. United went unbeaten in May, but then only took three out of 12 possible points in June.
United forward Charlie Davies is tied for the MLS lead in goals with eight, though four of those have come from the penalty spot.
PROBABLE LINEUPS
D.C. United (4-4-2):
Hamid, Woolard, White, McDonald, Kitchen; Pontius, De Rosario, Simms, Najar; Davies, Wolff.
INJURY REPORT
OUT: MF Branko Boskovic (L ACL tear); DF Dejan Jakovic (L hamstring strain); DF Devon McTavish (concussion); MF Santino Quaranta (concussion);
DOUBTFUL: DF Marc Burch (R hamstring strain);
QUESTIONABLE: FW Charlie Davies (R ankle sprain); MF Kurt Morsink (R ankle sprain); FW Joseph Ngwenya (R MCL sprain); DF Jed Zayner (L knee sprain)
Philadelphia Union
(4-1-3-2): Mondragon; Harvey, Valdes, Califf, Williams; Carroll; Mapp, Le Toux, Paunovic; Ruiz, Mwanga.
INJURY REPORT
QUESTIONABLE: FW Veljko Paunovic (L hip strain);
PROBABLE: DF Danny Califf (clavicle contusion); FW Carlos Ruiz (rib contusion)
Prediction
D.C. United 1-1 Philadelphia Union 
