Atlanta United's MLS title defence started with a loss on Sunday, while Los Angeles FC left it late.

Frank de Boer has endured a mixed start to life as Atlanta head coach and his side suffered a 2-0 loss to DC United at Audi Field in their MLS opener.

Paul Arriola scrambled in the opener for DC following a corner just before the break.

Luciano Acosta scored from 25 yards just before the hour-mark to double the hosts' lead, although Brad Guzan should have done better.

De Boer has lost two of his first three competitive games at the helm of reigning MLS Cup champions Atlanta, who reached the CONCACAF Champions League quarter-finals on Thursday.

In California, Los Angeles came from behind to claim a 2-1 win over Sporting Kansas City.

Krisztian Nemeth tucked away a pass from Johnny Russell to give Sporting a 16th-minute lead.

But Diego Rossi's curling strike drew LA level, and they were given a further boost when Sporting midfielder Roger Espinoza was sent off with six minutes remaining.

They made the most of their numerical advantage, substitute Adama Diomande turning in the area and finishing powerfully in the fourth minute of additional time.