Remedi scores 1st MLS goal, Atlanta beats NYCFC in 1st leg
Atlanta, which has won 11 of its 18 road games this season, hosts the second leg next Sunday.
Remedi tapped in a rebound after Josef Martínez's one-touch shot was blocked by Sean Johnson and settled against the post.
Johnson made a big save of Greg Garza's breakaway shot in second-half stoppage time.
Miguel Almiron appeared to open the scoring in the 20th minute but it was disallowed after a video replay ruled Atlanta was in an offside position during the buildup. Atlanta defender Franco Escobar sent a point-blank shot wide in the 34th.
NYCFC has reached the conference semifinals in three straight seasons but has lost the first leg in each.