The Colorado Rapids goalkeeper sustained the groin injury while taking a goal kick in the first half of the USMNT's 2-1 loss to Mexico at MAPFRE Stadium in Columbus and left the match in the 40th minute, replaced by Brad Guzan.
Howard “has returned to Colorado for further evaluation and to determine treatment plans,” stated the federation's press release.
His USMNT teammates flew to San Jose, Costa Rica on Sunday afternoon ahead of Tuesday's match at the Estadio Nacional (9 pm ET, beIN SPORTS, NBC Universo). The US are winless in nine previous qualifiers in Costa Rica.
The Rapids will resume their Audi 2016 MLS Cup Playoffs campaign on Tuesday, Nov. 22 with the first leg of the Western Conference Championship at Seattle (10 pm ET, FS1).