Peterborough gave their Sky Bet League One promotion hopes a boost with a 2-1 win at Leyton Orient.
Hector Kyprianou and Ephron Mason-Clark gave Peterborough a two-goal half-time lead before Orient midfielder Ethan Galbraith reduced the deficit after the break.
It took Posh just eight minutes to go ahead but they owed their advantage to a howler from Sol Brynn.
The goalkeeper on loan from Middlesbrough allowed a cross from Harrison Burrows to go through his hands and former Orient player Kyprianou was presented with the simplest of chances to grab his eighth goal of the campaign.
Promotion chasers Posh doubled their lead after 25 minutes after Josh Knight nodded a cross from David Ajiboye across goal and leading scorer Mason-Clark bundled the ball into the net for his 19th goal of the season.
Comfortable in the first-half, the visitors struggled to dictate in the second period after Orient made three half-time substitutions and when Galbraith reduced the deficit in the 66th minute, Posh were made to work hard to protect their lead.
Keeper Jed Steer was forced into a finger-tip save to deny Galbraith a second but the resilient visitors ran out worthy winners to maintain their automatic promotion hopes.