Moses Odubajo scored Leyton Orient’s first-ever away play-off semi-final goal to take a deserved draw into the home leg of their tie against Peterborough United.
The O’s reacted well to going behind to Britt Assombalonga’s 33rd goal of a productive season and arguably ought to have returned to Brisbane Road with a lead ahead of Tuesday’s tie after enjoying much the better of the game either side of Odubajo’s 11th of the season.
Russell Slade made one change from the side which won at MK Dons on the final day of the season, bringing Scott Cuthbert in for Gary Sawyer, who dropped to the bench.
Posh boss Darren Ferguson made eight changes after rotating heavily in the draw at Port Vale, with only Bobby Olejnik, Craig Alcock and Jack Baldwin retaining their places.
The O’s could have been ahead inside two minutes when David Mooney just failed to connect with Kevin Lisbie’s cross-cum-shot.
An Orient corner was headed out to the edge of the Posh penalty area before being helped back into the path of Lisbie, who from an acute angle, dragged dangerously across goal, but Mooney was unable to turn the ball home.
Peterborough responded almost immediately, Nicky Ajose crossing to the far post, where only the alertness of Elliot Omozusi denied Danny Swanson a free header from close-range.
After a frantic start, things calmed down until in the 16th minute, Peterborough took the lead through an offside Assombalonga.
Allowed too much space to stride forward, midfielder Danny Swanson tested Jamie Jones with a firmly-struck effort which the O’s goalkeeper could only parry into the path of full-back Mark Little, who crossed into the six yard box for Assombalonga to glance home.
The hosts thought they had a good shout for a penalty in the 29th minute when Nathan Clarke and Assombalonga tangled, but referee Graham Salisbury waved away the appeals.
Peterborough won a free-kick from a good position a few seconds later, with a well-worked routine releasing Ajose to shoot narrowly wide from 20 yards.
Mooney then tried his luck, sending an audacious overhead flick into the side-netting following a corner.
As the half came to a close, it was Orient who were on top, penning the hosts in their own penalty area with a string of set-pieces.
A minute before the break, Dean Cox saw his header blocked on the line after Posh keeper Olejnik missed Cuthbert’s long throw-in from the right.
Slade’s side broke against Peterborough a minute later, Cox wasting another good chance as he shot into the body of Olejnik with a low effort.
Peterborough began the second-half on top and Odubajo ought to have done better when he was released down the right.
The O’s winger had the beating of Posh full-back Kgosi Ntlhe, but could not pick out Lisbie in the middle, who had stolen a march on his marker.
From the resulting corner, Peterborough broke, with Assombalonga seeing his effort held by Jones from inside the penalty area.
Peterborough skipper Tommy Rowe had the hosts’ best opportunity following the restart, curling narrowly wide on his left foot from 18 yards.
Orient’s repeated failure to pick out the final ball was never more evident than in the 68th minute when Lisbie wasted their best chance of the game to that point.
Mathieu Baudry brought the ball out of defence, gallivanting into the Posh half before slipping the ball into the path of Lisbie, who cleverly jinked around his marker before firing wide with Mooney screaming for the ball in space to his left.
With 18 minutes left, Orient grabbed the equaliser which their showing since falling behind had merited.
Substitute Shaun Batt nodded into the path of Mooney, who shot on the turn, only to see Olejnik parry his shot into the path of Odubajo, who slotted into an empty net from six yards.
Cox nearly put the O’s in front a couple of minutes later when he thrashed a low effort towards the bottom corner, only for Olejnik to get down superbly and push around the post.
Olejnik denied Orient a winner with ten minutes to go, first saving Cox’s effort before superbly preventing Mooney’s follow-up as the linesman flagged for offside.
Peterborough United: Olejnik; Little, Alcock, Baldwin, Ntlhe; Swanson (Isgrove 71), Bostwick, Payne (McCann 81), Rowe (c); Assombalonga, Ajose (Washington 52).
Unused: Newell, Knight-Percival, McQuoid, Day (GK).
Leyton Orient: Jones; Cuthbert, Baudry, Clarke (c), Omozusi; Odubajo, Lundstram (James 70), Vincelot, Cox; Lisbie (Batt 70), Mooney.
Unused: Sawyer, Bartley, Dagnall, Ness, Larkins (GK).
Booked: Alcock for a foul (19); Ntlhe (90+5).
Attendance: 9,159 (1,710 Orient).
Referee: Mr G Salisbury.