Neither Michael Parkhurst nor Miles Robinson will be available for Thursday’s MLS playoff game against Philadelphia at Mercedes-Benz Stadium, Atlanta United manager Frank de Boer said Tuesday.

Both players are centerbacks. Robinson, who finished third in MLS Defender of the Year voting, sustained a strained hamstring while with the U.S. men's national team. Parkhurst, the team's captain, sustained a dislocated shoulder in last week's playoff win against New England. He is scheduled to undergo an MRI scan Tuesday.

Their absences mean Atlanta United has just three healthy centerbacks: Leandro Gonzalez Pirez, Franco Escobar and Flo Pogba. Should the team continue to use three centerbacks as part of its 3-5-2 formation, de Boer won't have any centerbacks remaining to include in his reserves for the game. De Boer said he won't hesitate to use all three centerbacks in the same starting formation, if that's what is needed.

De Boer said Robinson could play in the next round, should Atlanta United advance.