Seattle have been playing in front of crowds averaging over 36,000 and there may not be the usual frenzied support for the tourists that United often enjoy in such friendlies.
"What is nice for us is that when United come here, they are going to be the away team," Keller stressed to the official programme for the match. "They're not going to come here and have more support than us.
"It's a great standard that we've set in MLS to host these games and to have our team supported as the home team. It's something that Manchester United will know when they leave here. It's going to be a great showcase for us and MLS."