Columbus had only a few chances in the first half, but took advantage of the best one. Kevin Burns silenced the 31,311 in attendance — a US Open Cup record — in the 20th minute when he beat Kasey Keller.
Frankie Hejduk got behind the defense, ran to the byline and cut the ball back to Steven Lenhart just inside the area. With plenty of space to turn, Lenhart touched to Burns and his shot easily beat Keller.
Nyassi equalized in the 38th minute. Tyson Wahl's cross was punched away by Columbus keeper Andy Gruenebaum. But Nathan Sturgis fought for possession and was able to roll a pass to Nyassi, who caught Gruenebaum 10 yards off his goal line.
Nyassi, a 21-year-old Gambian midfielder, was one of Seattle's first signings after joining the MLS. It took him nearly two full seasons to score his first goal in America, breaking through last Saturday in a MLS match against Toronto. Now he's got three goals in two games.
The second goal came in the 66th minute. Ghosting in from the wing, Steve Zakuani got a clear header on Fredy Montero's cross but it hit the crossbar as Gruenebaum fell back into his net. Nyassi was unmarked and easily knocked in the rebound.
Columbus' Robbie Rogers hit the frame of the goal with a hard shot in the 85th minute, but Seattle held on in the closing stages.
