Marcus Maddison struck the only goal as Peterborough ended leaders Shrewsbury’s unbeaten start to the League One season.
Posh striker Maddison turned home Ryan Tafazolli’s cross in the 14th minute at London Road to secure his side’s first league win in seven matches.
But Shrewsbury, who began the day as the only unbeaten side in the Football League, remain top as Wigan were held to a goalless draw by 10-man Blackburn.
Blackburn held out for the final 32 minutes after midfielder Elliott Bennett had been sent off for his second yellow card.
Charlton stay fourth, level on points with Bradford, after Ricky Holmes’ second-half free-kick secured them a 1-0 home win against London rivals AFC Wimbledon.
Rotherham are sixth despite going down 3-1 at home to Gillingham, who struck with headers at the start of each half through Josh Parker and Tom Eaves.
Kieffer Moore replied for Rotherham with his 12th goal of the season, but Parker headed his second after home defender Joe Mattock had been shown his second yellow card.
Fleetwood clinched their first win in six league games, 2-0 at home against Oxford, as late goals from Bobby Grant and Jordy Hiwula halted the visitors’ five-match unbeaten run.
Oldham were beaten for the first time under manager Richie Wellens, losing 3-2 at home to Scunthorpe.
Tom Hopper and Josh Morris put Scunthorpe 2-0 up inside 10 minutes and, although Oldham hit back through Peter Clarke and Craig Davies, Duane Holmes put the visitors back in front two minutes later.
Simon Cox struck the only goal in Southend’s 1-0 win at Walsall and second-half goals from Tom Nichols and Rory Gaffney secured Bristol Rovers a 2-0 home win against MK Dons.
Bottom club Plymouth and Rochdale drew 1-1 at Home Park, where Matt Done struck a first-half equaliser for the visitors after Peter Grant had headed Argyle ahead after just 40 seconds.
Bury defender Eoghan O’Connell was sent off for his foul on John Marquis in first-half stoppage time and Ben Whiteman broke the deadlock for Doncaster, who won 1-0 at Gigg Lane.
In the 2pm kick-off, Northampton clinched back-to-back league wins as Sam Hoskins’ first-half goal sank Blackpool 1-0 at Sixfields.