Eddie Howe's Bournemouth side looked set to make it three wins out of three when Callum Wilson gave them a deserved lead after 58 minutes at Dean Court on Tuesday.
Forest had other ideas, though, and big-money signing Britt Assombalonga equalised nine minutes later, then strike partner Matty Fryatt popped up with a winner 18 minutes from time to stun Bournemouth.
Stuart Pearce's side moved to the summit after making it two wins out of three and Cardiff City occupy second spot following their 1-0 win over Wigan Athletic.
Nicky Maynard scored the only goal of the game at the Cardiff City Stadium against the team where he spent a loan spell last season, to ensure the Welsh side also have seven points as they attempt to return to the Premier League at the first attempt.
Wigan, on the other hand, have just one point to their name after also suffering a defeat at Charlton Athletic on Saturday.
Charlton's bright start to life under Bob Peeters continued with a 3-2 victory over Derby County, who had not conceded a goal in their first two Championship games.
George Tucudean, Yoni Buyens (penalty) and Igor Vetokele were on target to ensure that Jamie Ward's double proved to be in vain for last season's beaten play-off finalists at The Valley.
Millwall are the other side on seven points and sit in third spot after Magaye Gueye rescued a 1-1 draw with an equaliser deep into time added on at Sheffield Wednesday, who had led courtesy of a Chris Maguire goal.
Managerless Huddersfield Town got up and running with a surprise 2-1 victory at Reading, with recent signing Jacob Butterfield and striker Harry Bunn on target.
Sami Hyypia secured his first victory as Brighton and Hove Albion boss at the expense of Leeds United, who were beaten 2-0 at Elland Road.
Lewis Grabban scored twice as Norwich City beat Blackburn Rovers 3-1, while Blackpool are still looking for their first point after surrendering a lead to lose 2-1 at home to Brentford.
Christophe Berra scored twice as Ipswich Town twice came from behind to draw 2-2 at Birmingham City, Watford were 2-0 winners at Rotherham United and Middlesbrough beat Bolton Wanderers 2-1 on the road.
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