Roger Federer blamed the performance of team-mate Stanislas Wawrinka for Switzerland's 5-0 Davis Cup loss to the United States.
Mardy Fish defeated Wawrinka in five sets and John Isner overcame Federer in four during the first singles rubbers in Fribourg on Friday.
The combination of Fish and Mike Bryan then came from a set down to beat Federer and Wawrinka in the doubles, sealing an insurmountable 3-0 lead and booking the USA a place in the World Group quarter-finals.
"I played well enough in doubles, but Stanislas not so much," Federer said on Sunday.
"He (Wawrinka) didn't have his best match in singles. It's a shame, because of that defeat we weren't able to put the US under pressure."
"We just had a couple of games where we struggled too much and couldn't convert ourselves."
"They did really well and got the victory they deserved."
"We did have our chances but maybe they were just a touch better than us again today."
US team captain Jim Courier praised the spirit of his players, who overcame a partisan crowd and coped well with the high altitude in Switzerland.
"This was a big step forward for our guys to come in here and play against a team of this calibre," Courier said.
"Our attitude remained strong all the while and we were ready for whatever. That is what you need for any road tie."
Either France or Canada await the US in the last eight, with a potential semi-final showdown against holders Spain to follow.
"We have the worst draw you could have on paper," Courier said.
"But you saw what paper means here, which is absolutely nothing. That's the statement, it's that our guys are committed and played well."