The Cherries looked set to continue their 100 per cent start to the campaign when Callum Wilson, a summer signing from Coventry, struck his first goal at the Goldsands Stadium just before the hour mark to put Eddie Howe's men ahead.
But strikers Britt Assombalonga and Matty Fryatt netted in quick succession to earn Forest the 2-1 win and move Stuart Pearce's men to the top of the pile.
They were joined on seven points by Cardiff after Nicky Maynard came back to haunt the side he finished last season with. The former Latics loanee scored the game's only goal in the 53rd minute to leave Wigan without a victory this season.
A last-gasp leveller from Magaye Gueye earned Ian Holloway's Millwall a 1-1 draw at Sheffield Wednesday as both sides stayed in the top half and there was also late drama in Birmingham where Christophe Berra nodded home his second of the night deep into added time to earn Ipswich a 2-2 draw.
Charlton, many people's favourites for relegation, pulled off one of the eye-catching results of the night as they saw off last season's play-off finalists Derby 3-2 at The Valley despite Jamie Ward celebrating his new deal with two goals for the Rams.
Liverpool loanee Joao Carlos Teixeira helped earn Reds legend Sami Hyypia his first win as Brighton boss. Kazenga Lua Lua struck with six minutes to go to seal the 2-0 win over Leeds after Teixeira's fifth-minute opener.
There was also a first win of the campaign for managerless Huddersfield who beat Reading 2-1 thanks to goals by Jacob Butterfield and Harry Bunn.
The quickest goal of the night came at Carrow Road where Blackburn's Tom Cainey opened the scoring after 49 seconds but two late goals eventually saw Norwich run out 3-1 winners.
Elsewhere there were away wins for Watford, who saw off Rotherham 2-0, and Middlesbrough who came from behind to beat Bolton 2-1 with summer acquisition Kike grabbing the winner.
Brentford also showed resilience after conceding first to earn their first three-point haul of the campaign by the same scoreline, a result which piled more misery on a new-look Blackpool side.
Assume that's Assombalonga in the pic there; he's a strapping young fellow isn't he? Strewth- Ezy_Rider