Charlie MacDonald grabbed a brace as Leyton Orient breezed past Bournemouth.
David Mooney set up MacDonald for the opener and the striker added his second after the break, coolly converting Mathieu Baudry's cross.
Substitute Brett Pitman gave the Cherries a lifeline when he drilled in Eunan O'Kane's centre.
But Kevin Lisbie, on his return from injury, made sure Orient took all three points when he received a pass from Moses Odubajo and slotted home.
The result means Bournemouth have lost their last four games and are two points off the play-offs in seventh, while Leyton Orient move up to 11th.
VIEW FROM THE DRESSING ROOM
Bournemouth manager Eddie Howe told BBC Radio Solent:
"At any level you play you can't give teams goals and I felt we did. The first two goals were really disappointing.
"Leyton Orient didn't work hard for them, we gift-wrapped them and unfortunately it's just crept into our game the last few weeks, something we need to address immediately.
"The players that are playing are good enough, they've proved that. We've won with this team so we need to learn our lessons again from today.
"We scored a great goal and we were back in the game at 2-1, it was game on and we were the team in the ascendancy for long periods after that. We had enough chances first half to have got more, but once the third goal goes in, it's very difficult."