Hector Kyprianou gave hosts Peterborough the lead in the 21st minute but Omar Beckles levelled for Orient 13 minutes later.
The point was enough to see Posh end a three-match losing run in the league.
Peterborough opened the scoring when Harrison Burrows’ deep corner was helped back across goal by Josh Knight for ex-Orient man Kyprianou to hook in from point-blank range.
It was the third goal of the campaign for the Cypriot midfielder, who failed to score in 66 league appearances for the O’s.
Orient were back on level terms in the 33rd minute when Beckles was credited with the touch as both he and Joe Pigott threw their heads at a fine cross from the right by Jordan Graham.
A smart Sol Brynn save prevented Peter Kioso from restoring the Posh advantage before the break.
Brynn again impressed when keeping out an acrobatic Ephron Mason-Clark effort just before the hour mark while substitute Ethan Galbraith blazed Orient’s best opportunity of the second period over the crossbar.
Kwame Poku put Posh ahead when he fired home Ephron Mason-Clark’s cross, but they missed the chance to double the lead when Mason-Clark saw his penalty saved by Dan Grimshaw after being brought down by Matt Pennington.
Blackpool’s task became harder when Olly Casey was dismissed early in the second half for bundling over Ricky-Jade Jones and the visitors added insult to injury when Harrison Burrows netted the resulting free-kick.
Nicholas Bilokapic denied Sonny Carey twice in quick succession as Blackpool sought a response, but Poku slipped in Jones before the hour for Peterborough’s third to seemingly put the game to bed.
But the hosts scored twice in the space of four minutes through Kenny Dougall’s header and Carey, who was first to the rebound when Bilokapic parried James Husband’s shot to set up a grandstand finish.
Posh held firm, however, and Mason-Clark put the result beyond doubt in stoppage time with a close-range finish to lift his side to fourth.
Darren Ferguson’s promotion chasers dominated possession but failed to break down their hosts.
Michael Skubala’s Imps are still waiting for a first win since the end of November, a run which has now stretched to nine games.
But a second goalless draw on the spin, and a third game without defeat, is a boost after four defeats in a row over the festive period.
There was a lack of chances in the first half as the two sides largely cancelled each other out.
Lasse Sorensen squandered a good chance for the hosts when he fired wide at the near post and Posh goalkeeper Jed Steer did well to hold on to Ethan Erhahon’s curling strike.
Peterborough hit the crossbar late in the half through Ricky-Jade Jones’ deflected effort.
Lincoln’s Lukas Jensen then produced a good save to beat away Harrison Burrows’ strike.
At the other end Steer superbly kept out Reeco Hackett-Fairchild’s effort, while Danny Mandroiu missed the target with a glorious chance.
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.
First-half goals from Joel Randall and Ephron Mason-Clark put the hosts in cruise control, before Cole Stockton’s own goal and a Kwame Poku close range finish completed the rout after the break.
The visitors will be left wondering if this match may have had a different outcome if Stockton’s first-half stoppage time volley had not been headed off the line by Posh defender Josh Knight.
Yet, in truth, this was a richly-deserved victory for Darren Ferguson’s men and the scoreline did not flatter the Scot’s side at all.
Randall opened the scoring in the sixth minute when he coolly side-footed in Peter Kioso’s cross at the far post.
The visitors then survived a decent penalty shout on 19 minutes when Poku was felled by Mark Helm’s clumsy challenge on the byline.
Mason-Clark fired in Posh’s second goal in the 44th minute after Ciaran Gilligan’s slip had allowed Archie Collins to pick him out inside the Burton penalty box.
Albion striker Stockton then scored at the wrong end, turning Poku’s driven cross past his own goalkeeper Max Crocombe just past the hour to make it 3-0.
Ghanaian midfielder Poku finally got the goal his energetic performance deserved when he bundled in Harrison Burrows’ cross from the left in the 66th minute.
The result means Ferguson’s fifth-placed team have dropped just two points from their last six games at London Road.
Out-of sorts Burton, who handed 17-year-old centre-half Will Tamen his league debut, have slipped to 17th in League One.
Goals from Jack Taylor, Joe Ward, Kwame Poku and Jonson Clarke-Harris sent the home fans into hysteria ahead of Thursday’s return leg at Hillsborough.
Posh – who saw Darren Ferguson return for a fourth stint as manager at the start of the year – were delirious after sealing the last play-off spot as they leapfrogged Derby on the final day and they are in dreamland once again after blowing the visitors away in the first leg.
And it could be another fairytale finish to the season for Ferguson who has steered the club to the Championship on three separate occasions as well as a League Two promotion.
Darren Moore’s Sheffield Wednesday were gutted to only be in the play-offs after securing a club record 96-point haul.
They now hold the unwanted record of the highest points total ever to miss out on automatic promotion in the Football League.
A dismal run of just four points from a possible 24 heading towards the run-in cost them dear.
And the Owls, who missed out on a return to the Championship after play-off heartache to Sunderland last season, were the architects of their own downfall once again.
Moore’s charges have an absolute mountain to climb to keep their dreams of a second-tier return alive.
The visitors had the first real chance of the encounter as Michael Smith got in behind but Will Norris came out on top with a good save.
It was a mistake from Owls goalkeeper Cameron Dawson which opened the floodgates for free-flowing Posh.
There was an initial poor clearance which fell to Taylor as he fired home a shot which inexplicably crept under Dawson in the 20th minute.
And things went from bad to worse as a wicked deflection doubled the hosts’ lead 16 minutes later.
It was a good strike from Ward, but was ultimately flying wide before it took a big deflection which allowed the ball to dip up and over Dawson off the underside of the crossbar.
Wednesday had a couple of big chances to cut the deficit before the break.
They both fell to Josh Windass, who was first thwarted by a good Norris save before he headed over the target.
Moore’s side missed another glaring opportunity when Michael Ihiekwe nodded a teasing Barry Bannan cross wide.
And they were instantly made to pay as unmarked Poku headed home – his sixth goal of the season – as Posh flew into a 3-0 lead.
The Owls were unlucky not to get a penalty when Marvin Johnson’s strike hit Ronnie Edwards’ elbow, but the referee waved away huge appeals from the on-rushing Wednesday players before Ihiekwe’s effort from the resultant corner was cleared off the line.
And with 15 minutes to go, the former Rotherham man saw a second strike hacked off the line as Wednesday’s night followed a similar tone.
Clarke-Harris hit his 29th goal of the campaign as he easily nodded home at the back post after Taylor chipped the ball up at the back post after he was denied by Dawson.
It could have been even more had it not been for a late Dawson save.
Archie Collins netted the winner in the 42nd minute to lift Posh up to second, one point above Oxford.
The visitors could have been ahead in the second minute when Ricky-Jade Jones fired over from close range while Kwame Poku stung the palms of Jay Lynch in the Fleetwood goal moments later.
Posh finally got the breakthrough they deserved when Collins’ long-range effort appeared to take a deflection before flying past a helpless Lynch just before half-time.
United continued to dominate after the break and could have doubled their lead in the 51st minute when Lynch brilliantly stopped Jade-Jones’ close-range header.
Fleetwood’s best effort came in the 64th minute when Posh goalkeeper Nicholas Bilokapic pulled off a good save to keep out Maleace Asamoah’s curling effort.
Further chances fell to the visitors in the closing stages with Ephron Mason-Clark and Jade-Jones coming close to extending their lead as Darren Ferguson’s side made it five league games unbeaten and condemned Fleetwood to a sixth consecutive defeat in all competitions.
The Valiants had their chances in an even contest at Sixfields but were plunged deeper into relegation trouble by Mitch Pinnock’s sweet first-half strike and a stoppage-time second from Shaun McWilliams.
Vale remain in the relegation zone in League One, a point from safety, with six games to play.
“It’s bitterly disappointing,” said Moore. “We had as much of the play as they did but the game was decided on chances – they converted theirs, we didn’t convert ours.
“I thought we looked a bit on the back foot. I’m not sure if the game on Friday took it out of us so I’ll look into that, but the chances were there for us.
“We weren’t at our sharpest and we couldn’t capitalise in those key moments. I spoke to the boys at half-time about showing that ruthless mentality when you get chances.
“If you put those chances away it’s a different game and they were gilt-edged chances as well, but there was no real conviction when we did get in there and that’s really disappointing.
“The fact that their goalkeeper got man of the match tells you how the game went, but we have to move on quickly.
“Other results have gone our way but that’s only a very small consolation because we want to do it our way and not rely on other teams.”
The win took Northampton up to 56 points – the club’s highest tally in League One for 16 years – as they all-but secured safety.
“I’m pleased with the result and it took a lot of hard work from the boys against a team who are fighting for their lives and have won their last two,” said manager Jon Brady.
“To score two goals against them was really pleasing and now we’ve hit the target that we set for ourselves at the start of the season, which is really pleasing.
“The target was 54 points and there were various reasons behind that, so to eclipse that with four games to spare is a fantastic effort and it’s testament to the staff and the players.
“We’ve worked so hard all season and I was delighted with how the boys performed today. We changed shape to 3-4-3 to match their physicality and I thought the way we sat in our shape was really strong.
“We landed on second balls and broke on them well and that was really important, so overall I thought it worked and we deserved to win the game.”
Ben Garrity’s opener was added to after half-time by James Wilson and Nathan Smith for a first win in three matches.
CJ Hamilton’s early attempt was thwarted by Vale stopper Connor Ripley, while Vale’s Uche Ikpeazu lashed wide before 10 minutes.
Jordan Rhodes beat the offside trap but not Ripley as the Seasiders pressure continued, with Albie Morgan firing wide before the half-hour.
Morgan then blasted over from distance but Garrity put Vale ahead after racing clear to slot past Dan Grimshaw in the 39th minute.
Grimshaw tipped Ikpeazu’s thunderbolt over in first-half stoppage-time, with the Tangerines stopper denying Jack Shorrock after half-time.
Ripley thwarted Blackpool’s Kyle Joseph before Wilson’s sublime effort from outside the box doubled Vale’s advantage after 57 minutes.
Oliver Casey fired straight at Ripley and later struck the post from Karamoko Dembele’s corner.
Vale’s third came after Smith scrambled home from a corner with 10 minutes remaining, while Blackpool’s Callum Connolly dragged wide before the end.
Andy Crosby’s men arrived in Hertfordshire on the back of three straight defeats and no win in five and Connor Ripley kept Jake Forster-Caskey and Jamie Reid’s efforts out either side of half time to ensure a point for the visitors.
The away side started well as Ben Garrity saw his shot blocked and Funso Ojo’s well-struck shot from range was saved by Taye Ashby-Hammond from the resulting corner.
Boro started to come into the game before the half hour mark when Forster-Caskey’s effort was well-saved by Ripley before Nick Freeman’s follow-up was blocked.
Dan Butler’s pinpoint cross then picked out Forster-Caskey, who fired over from close range.
Ripley had to be on hand once again after the break, standing firm to deny Reid after he was out through on goal.
Stevenage kept up the pressure as they tried to force a winner, but Jason Lowe was on hand to block Elliott List’s effort late on.
A 10-minute burst either side of half-time saw Ben Garrity and Baylee Dipepa do the damage for Darren Moore’s men in the Sky Bet League One contest at Vale Park.
Buoyed by a first victory of the year against Burton last time out, the hosts flew out of the blocks.
Rovers goalkeeper Jed Ward produced a decent early save from James Wilson’s header.
And he needed to make an even better one to keep out Alex Iacovitti on the 20-minute mark.
Moments later, the Gas were saved by the post as Garrity and Wilson, who was later forced off through injury, tried to bundle the ball home.
Vale had their deserved lead on the stroke of half-time as Garrity nodded home the opener in the 42nd minute.
After the break, Ryan Loft saw a header go wide of the mark as Vale pushed for a second.
They got it when substitute Dipepa dazzled his way through the visitors’ defence before coolly slotting home in the 52nd minute.
Substitute Rhys Walters had his overhead kick saved by Ward with 10 minutes to go.
Hicks awarded an 88th-minute penalty to the visitors when Conor Grant brought down Abu Kamara and Colby Bishop converted to keep Pompey top of the table.
The home fans were furious as they felt they had a strong claim for a free-kick seconds earlier, with one supporter entering the pitch and chasing after the official before the coaching staff on the touchline intervened.
A statement from Port Vale on their X account read: “Port Vale Football Club condemn the actions of the individual who entered the field of play during today’s match against Portsmouth.
“We will work with the relevant authorities to ensure the matter and the individual is dealt with a zero tolerance approach.
“We remind all supporters that entering the field of play is a criminal offence.”
The Valiants sit just three points above the relegation zone in 20th spot following the defeat.
The victory takes Pompey six points clear of second-placed Bolton.
In a fiercely-contested first half, Bolton should have taken the lead after 28 minutes. A powerful header by Jon Dadi Bodvarsson was brilliantly pushed away by Will Norris, and from six yards out, and with an open goal, Dion Charles somehow fired the rebound wide.
Pompey then had the ball cleared off the line after 43 minutes as Yengi’s shot was partly blocked by goalkeeper Nathan Baxter before Gethin Jones hooked it away.
Right on half-time a corner kick by Jack Sparkes was met by Shaughnessy to glance his header into the net.
Pompey controlled the second half and deserved their second goal two minutes from time as Yengi hammered home from six yards from a Gavin Whyte cross.
The visitors were never in any danger once Sean Raggett headed them into an early lead, and Paddy Lane’s brace either side of half-time ensured they would go back above Bolton.
Will Norris made a couple of routine saves from Mitch Pinnock and Sam Hoskins in the early stages before Pompey struck in the 11th minute when Raggett headed in a Jack Sparkes corner.
That settled the visitors and they should have added another when Kusini Yengi struck the crossbar with the goal at his mercy.
But it was not long until a second did arrive as Lane lifted over goalkeeper Max Thompson in the 26th minute after being sent through by Christian Saydee.
Northampton’s best chance of the first half was headed wide by Kieron Bowie and they fell further behind soon after half-time when Lane converted Alex Robertson’s cross.
The result was not in doubt and Portsmouth coasted through the rest of the game without any problems.
Bishop bagged his 11th of the season to set John Mousinho’s side on their way to victory and Robertson’s first senior goal gave them second-half breathing space.
With both sides having conceded four goals on their way to defeats at the weekend, it was perhaps unsurprising this game had something of a cagey start.
The visitors saw plenty of the ball early on but struggled to create anything to test Max Crocombe in the Burton goal while Will Norris at the other end had to deal with shots from Kwadwo Baah and Mark Helm.
Bishop finally broke the stalemate in the 38th minute when he fired home Pompey’s first shot on target from the penalty spot after Steve Seddon had brought down Abu Kamara.
Pompey doubled their lead, slightly against the run of play, with Manchester City loanee Robertson finding the corner to finish Joe Rafferty’s cross on 63 minutes.
Albion played the six minutes of stoppage time with 10 men after Seddon, booked when conceding the penalty, picked up a second caution for another challenge on Kamara.
The hosts started well with Mo Eisa curling a shot just over the crossbar.
They took the lead after 24 minutes when a nice move down the left ended with Reece Cole cutting the ball back to Vince Harper to tap in for his first goal for the club.
The home side were in complete control with Fleetwood’s first effort at goal coming after 42 minutes, when Ben Heneghan headed over from close range.
Furious Fleetwood boss Charlie Adam made a quadruple change at the break and the Cod Army looked much better with Carl Johnston forcing Vili Sinisalo into a smart save.
Then Brendan Wiredu headed in from a corner, but the goal was disallowed for a foul on the Exeter goalkeeper.
Boson Lawal skied a good chance over the crossbar before Fleetwood grabbed an equaliser after 74 minutes when Promise Omochere was played in by Lawal and slotted the ball past Sinisalo.
Both sides had half-chances in the closing stages but lacked the quality to finish them off as the spoils were shared to leave the hosts 14th and Fleetwood second-bottom.
Around 1,000 Royals supporters entered the pitch in the 16th minute of the match on January 13 in protest against the club’s owner Dai Yongge.
The EFL has announced that the club have now come to an agreement over the suspended points penalty, which is line with a sanction handed to Blackpool in similar circumstances in 2015.
The match itself will be replayed in full on Tuesday, February 20, the EFL has confirmed.
All four goals came during a rip-roaring first half dominated by the home side, who have shown a marked improvement under boss Darrell Clarke.
David Button denied Liam Sercombe, George Lloyd and Lewis Freestone as Reading were forced to withstand considerable pressure.
But the opener arrived in the 29th minute with Sercombe sliding to touch Sean Long’s low ball in from the right.
The lead was doubled in the 37th minute when Button blocked an effort from Freestone only for a clearance from Amadou Mbengue to hit his own goalkeeper and fly into the net.
The overworked Button denied Ben Williams in the 42nd minute but the game then turned with Lewis Wing’s corner headed in at the back post by Jeriel Dorsett in the 45th minute.
Then, two minutes into time added on at the end of the first half, Wing’s cross was glanced into the net by Paul Mukairu.
Wing’s free-kick was pushed away by a diving Luke Southwood in the 69th minute and Nathan Butler-Oyedeji curled one just wide for Cheltenham deep into stoppage time as it finished all square.
The Royals recorded their biggest win for over a century in midweek, dispatching Exeter 9-0 in the EFL Trophy, but were brought back down to earth on their return to Sky Bet League One action as the hosts raced into a 3-0 lead after 31 minutes.
Three half-time substitutions from Selles did not turn the tide as Rhodes completed his first hat-trick for nearly four years shortly after the break, with Sam Hutchinson’s deflected strike nothing more than a consolation for a Royals side who remain rooted in the bottom four.
“It was not good enough,” Selles said. “We conceded the first goal and then we started to do things we just don’t do.
“We conceded three goals in the first half – and that’s not acceptable. It was nowhere near good enough from any of us today.
“At 3-0 down, I made changes because it was a very radical moment in the game.
“The first 10 or 15 minutes of the game we were not able to control the ball, pass and do the things we usually do.
“We were not able to apply the press and win the second balls in transitions, and the opposition was able to do it.
“We needed something radical to change the dynamic of the game. We got it, but we conceded another goal. That killed our wish to get back into the game.”
Hutchinson’s foul on CJ Hamilton gave Rhodes the chance to open the scoring from the spot and he followed up with a sweet strike into the corner after debutant Kylian Kouassi’s bullet header had doubled the lead.
Rhodes killed off the contest six minutes into the second half and Blackpool boss Neil Critchley had nothing but praise for his side.
“I’m really pleased with that performance,” he said.
“We showed a good response from losing last week. This was more of a Blackpool performance, more of what you associate with a group of players that represents the club and the way that I want them to.
“We took the game to them. I’m delighted with some of the performances, the team and Jordan obviously getting his hat-trick.
“We thought we could get some joy running at their full-backs and that’s how it turned out.
“Sometimes it works and sometimes it doesn’t. We live in a world of extremes, sometimes you get it right and you’re a hero. But then if you get it wrong you’re an idiot.
“It’s great for the supporters and now we have got to back that up with a good performance against Barnsley next week.”
Carlisle skipper Sam Lavelle sparked a spell of four goals in 13 first-half minutes when turning a cross into his own net under little pressure.
Luke Plange levelled quickly for the visitors but Harvey Knibbs struck twice to make it 3-1 to the hosts at the interval.
Lewis Wing and Femi Azeez completed the Reading rout with fine finishes in the final 12 minutes.
After a scrappy opening, the game burst into life in the 26th minute when Lavelle diverted a low cross from Jeriel Dorsett into his own net.
The visitors were back on terms just three minutes later when Plange tucked home a close-range volley, before Knibbs pounced in the 32nd and 39th minutes to give Reading a healthy half-time advantage.
Knibbs’ first came after an Azeez cross and scramble in the Carlisle area, his second following a neat turn and shot past keeper Tomas Holy.
Carlisle offered more enterprise going forward after the break but Wing thundered in a superb first-time effort in the 78th minute and Azeez proved similarly clinical five minutes later.
