Eddie Howe accused his Bournemouth side of dropping their standards after they surrendered an early lead to lose 3-1 to south-coast rivals Southampton.
Nathan Ake's sixth-minute strike had given the Cherries the perfect start at the Vitality Stadium but Ryan Bertrand's quick response and Jay Rodriguez's second-half double saw the Saints claim only their second away win of the season.
"Credit to Southampton, they played well today and deserved to win," Howe told Sky Sports. "We weren't at our best physically or technically today so there's a lot to learn from.
"I sensed it straight away, we weren't at our normal levels and struggled to get the amount of pressure we wanted on them. Technically we were also under the standards we've set."
Howe highlighted Bertrand's 14th-minute equaliser as the turning point in the game, adding: "It was a key moment.
"We were value for our goal lead. We started well and had a few chances we could have done better with on the counter. Defensively it was a poor goal to concede."
Sunday's fixture, Bournemouth's third in eight days, saw them fail to build on Tuesday's encouraging 1-0 victory over Premier League champions Leicester.
And Howe conceded a congested fixture schedule may have caught up with his side.
"When you look back perhaps the Leicester game took more out of us than we realised," he said.
"After three games in eight days, perhaps we could have rotated more. These are all things I'll think about.
"I and hopefully the players don't need reminding how difficult this league is, it's incredibly tough and the intensity levels are extreme.
"The players have to go through a lot physically over 90 minutes. It's a bad day at the office for us but we've got to bounce back."