Peterborough United played the last 30 minutes with 10-men, but hung on superbly to clinch a 1-0 win over Chesterfield to make it five wins from six in Sky Bet League One under Dave Robertson.
The visitors made a bright start and had two early efforts towards goal with Drew Talbot's volley deflected wide and then Jay O'Shea found the roof of the net with a speculative volley from the edge of the box.
Goalkeeper Ben Alnwick made a fine double stop to deny Jay O'Shea on the quarter hour mark as the visitors once again demonstrated their ability on the ball to create an opportunity in front of goal.
A superb Taylor cross was met by Luke James on 21 minutes, but the former Hartlepool man couldn't keep his header down at the near post. The deadlock was broken on 27 minutes as excellent approach play from Washington down the left saw the ball bobble into the path of Michael BOSTWICK and his shot was deflected past Lee and into the net.
Luke James was immediately denied a second after bursting into the box, but his volley was pushed away by Lee. Bostwick stabbed wide at the back post after Santos flicked on an in-swinging corner from Newell on 37 minutes.
Bostwick and Washington linked well on the edge of the box as the first half drew to a close, but the former fired wide.
Moments after the re-start, Posh came close to a second as a loose ball was deflected into the path of Washington, his left-foot strike was parried by Lee just out of the reach of the onrushing Bostwick.
Alnwick beat away a fierce drive from O'Shea and from the resulting corner made an even better save, pushing a back-heeled volley from Hird over the crossbar.
Washington saw a shot blocked after excellent approach play by the hard-working James before Alnwick denied Gary Roberts' at the other end after a swift counter attack.
Santos was cautioned on 62 minutes for a foul. He received a second yellow card moments later for a foul on the edge of the area, leaving Posh to play the final 28 minutes with just 10-men.
Dave Robertson made an immediate change with Michael Smith replaced by Shaun Brisley. An excellent run down the right from James saw him pull the ball back for Washington on 68 minutes, but the striker couldn't force the ball past Lee.
Confusion between Zakuani and Alnwick nearly led to the equaliser, the centre back ended up toe poking the ball against the outside of his own post.
On 79 minutes, Alnwick produced arguably his best save of the game to date, diving full length to push a pearler from Roberts around the post. Newell was booked for time wasting by Mr Webb on 83 minutes.
Chesterfield introduced Diesruvwe from the substitutes bench with five minutes to play. Morsy curled inches over the top from 25-yards on 86 minutes after a fine clearing header from Brisley from a right wing cross.
Five minutes added time was signaled by the fourth official as Posh desperately tried to cling on. And cling on they did with a steely determination and a huge effort from both the players and fans.
Full-time: Peterborough United 1-0 Chesterfield
Posh: Alnwick, Smith (sub Brisley 63min), Ntlhe, Bostwick, Taylor, Payne, James, Washington, Newell, Santos, Zakuani. Unused subs: Henry, Vassell, Mclean, Norris, Anderson, Beautyman.
Chesterfield: Lee, Darikwa (sub Jones 73min), Hird, Morsy, Ryan, O'Shea, Roberts (sub Dieseruvwe 84min) , Clucas, Evatt, Banks (sub Ariyibi 62min), Talbot. Unused subs: Chapman, Carter, Humphreys, Onovwigun,
Attendance: 6,612 (674 Chesterfield fans).