Peterborough United were knocked out of the FA Cup after a 1-0 defeat to Colchester United at the Weston Homes Community Stadium as a late George Moncur strike saw the U's progress into the third round of the competition.
Aaron Mclean had the first effort of the game on 18 minutes, but his shot was weak and Walker made a routine save. Joe Newell then saw a free-kick deflected behind for a corner kick after Oztumer was felled.
George Moncur tested Alnwick from 25-yards with the Posh shot-stopper beating the effort away. Sanchez Watt was cautioned for the umpteenth foul, the latest of which came on the Posh skipper Payne just on the half hour mark.
Eastman guided a shot wide following a low Kpekawa cross on 36 minutes.
Five minutes after the re-start, Mclean was presented with a golden chance to break the deadlock after a glorious pass from Bostwick, but his first touch was heavy and his shot was blocked.
Mclean saw a shot well blocked after a well-worked Posh free-kick involving Joe Newell after Washington had been upended in a wide area.
Mclean saw a volley go straight at Walker on 62 minutes after a link with Oztumer who was growing into the game in terms of his influence.
Colchester made the first change with 10 minutes to go as Rhys Healey replaced Massey.
On 84 minutes, Walker pushed a fierce Anderson shot around the post after letting fly from 25-yards.
Posh had the golden chance to break the deadlock three minutes from time as Watt brought down Bostwick for a penalty kick, but Mclean saw his spot-kick superbly saved by Walker.
From the resulting corner kick, Burgess saw his downward header strike the bar before being cleared.
However, deep into stoppage time, Colchester won it as Posh failed to clear and MONCUR calmly side-footed the ball into the corner.
Final Score: Colchester United 1-0 Posh
Colchester: Walker, Hewitt, Gorkss, Eastman, Kpekawa; Moncur, Fox, Eastmond; Watt (sub Clohessy 90min), Massey (sub Healey 80min), Sears. Unused subs: Lewington, O'Donoghue, Szmodics, Sembie-Ferris, Bonne.
Posh: Alnwick, Ntlhe, Bostwick, Burgess, Zakuani (sub Vassell 90min), Payne (sub James 90min), Anderson, Newell, Oztumer, Washington, Mclean. Unused subs: Henry, Smith, Mendez-Laing, Da-Silva-Lopes, Santos.
Attendance: 2,905 (404 Posh fans).