Goals from Deshorn Brown, Ian Harkes and Lloyd Sam appeared set to snap DC's three-match losing streak in MLS.

But the Sounders scored four goals in 27 minutes, including a 78th-minute winner, to complete a sensational comeback.

Meanwhile, New York Red Bulls made light work of San Jose Earthquakes, Austrian winger Daniel Royer scoring twice at the death to seal a 5-1 win.

Seeking back-to-back wins, Sean Davis gave the Red Bulls a 38th-minute lead courtesy of a powerful half-volley.

Sacha Kljestan and Felipe Martins put the result beyond doubt with goals in the 73rd and 75th minutes.

The Earthquakes managed to pull a goal back thanks to substitute Valeri Qazaishvili with two minutes of normal time remaining.

But the Red Bulls had the final say, Royer netting a fourth from a tight angle in the 90th minute before sealing the rout a minute later.

The Red Bulls are fifth in the Eastern Conference, 10 points adrift of leaders Toronto FC, which salvaged a last-gasp 2-2 draw at New York City.

David Villa's 13th goal of the season cancelled out Ashtone Morgan's opener before Maximiliano Moralez's 56th-minute effort put NYC – third and five points off the pace – ahead.

But Victor Vazquez successfully converted a penalty in the first minute of stoppage time to earn a share of the points for the Canadian visitor.

After pushing Manchester United in a 2-1 friendly loss on Tuesday (AEST), Real Salt Lake – which finished with 10 men – eased past nine-man Portland Timbers 4-1.

LA Galaxy lost 1-0 at home to Vancouver Whitecaps, Montreal Impact edged Philadelphia Union 2-1, while Minnesota United and Houston Dynamo played out a scoreless draw.