Jim Mallinder tore into Northampton Saints after Saturday's 55-24 defeat against Saracens at Twickenham.
Saints' under-pressure director of rugby, whose side stumbled to a seventh-placed finish last season, saw Sarries run riot to score seven of their nine tries in the first half.
Despite an improved second-half showing from his men, Mallinder pulled no punches in his post-match assessment.
"It's infuriating, it's embarrassing, it's disappointing," he said.
"You think you prepare properly and you think we had a good pre-season. We thought we were ready for it, but clearly we weren't. The first half, Saracens were clinical.
"Next week is big for us. We need to be better. We have played in some big games against Leicester, but next week is massive. It's vital for us that we get a win and get our season going."
Sean Maitland was Sarries' hat-trick hero, while Schalk Brits capped a superb display with a try of his own.
Victorious boss Mark McCall reserved particular praise for the latter as the South African proved he can still mix it with the best at the age of 36 in what looks set to be the veteran's final campaign.
"He's Peter Pan," said director of rugby McCall. "He's an explosive athlete and his athleticism hasn't gone away. His body is sore after games, but it was a stunning performance - he was incredible.
"This is his ninth season at the club and he's been a star from day one. He seems to save all of his best performances for Twickenham. He's a phenomenal player and hopefully we can give him a really good send-off this year."