David Accam scored for Chicago Fire but it wasn't enough as the hosts were beaten 4-3 at home by Kwadwo Poku’s New York City FC.
The Ghana international scored from the spot kick in the 72th minute to set up a tense final 20 minutes. He also provided the assist in Kennedy Igboananike’s goal for Fire.
Thomas McNamara's 10th-minute bending golazo was only the first in a seven-goal thriller at Toyota Park.
The Fire managed to equalize momentarily through Razvan Cocis before NYCFC's young wingers – Tony Taylor and Khiry Shelton – reestablished the visitors' two-goal lead.
Kennedy Igboananike scored early in the second half to bring the Fire within a goal, but a fourth NYCFC strike – a stunner from Mix Diskerud – was too much for Chicago to overcome.
New York City FC had Ghana striker Kwadwo Poku on their bench.