Orient secured a crucial point at home to Sheffield United thanks to Dean Cox's unstoppable volley on 82 minutes, sending them back to the top of League One after Wolves were beaten by promotion rivals Peterborough.
Despite their delight at regaining the top spot, the O's will probably feel as though they should have taken all three points after failing to find the net with a number of good chances in the first half especially.
As it was, the away side were first to strike when they took the lead through Conor Coady on 67 minutes after some poor defending allowed him to sneak in at the back post and squeeze a shot past Jamie Jones.
However Orient rallied after going behind and Cox scored yet another screamer from 25 yards to add to his collection and fire Orient above Wolves in the table.
The O's came into the game having bounced back well from the 1-0 home loss to Preston a fortnight ago, picking up four points from two difficult away trips to Swindon and Bristol City over the past week.
However Russell Slade will have been keen to get back on track at Brisbane Road today against a club where he spent much of his early career in coaching.
The Yorkshire side have not enjoyed the best of season’s so far this campaign and have spent the majority of it lingering in the relegation zone, but knew a win or a draw today would give them a good chance of climbing out of the bottom four.
Slade was forced into making one change from the side that drew with Bristol in midweek; Shaun Batt replacing the injured Kevin Lisbie. Meanwhile Blades boss Nigel Clough brought Harry Maguire and Jose Baxter in for Shaun Miller and Simon Lappin after they were held by Walsall - Orient's opponents in next week's FA Cup tie - on Tuesday.
It was a lively start to the game and an early chance fell to Mathieu Baudry on four minutes when his central defensive partner Nathan Clarke launched a long throw-in into the mix but the Frenchman couldn't control his close-range shot which went high and wide of the target.
Clarke himself came close opening the scoring shortly after when he was denied by visiting keeper George Long after a quickly taken corner from Lloyd James caught Sheffield United off guard.
The O's were well and truly on top in the opening exchanges - Batt and Moses Odubajo's pace allowing them to get in behind the opposition's defence on several occasions, forcing a number of corners in the process.
But the first clear-cut chance of the game fell to David Mooney with just over 20 minutes played. His clever run was brilliantly picked out by Dean Cox's threaded pass - it looked destined to be a goal given Mooney's form so far this season but the club's top scorer dragged his shot well wide of the left hand post, much to the relief of the Blades.
The game leveled out for a spell after this but the Irishman was handed an even better opportunity than his first on the half-hour mark. Again, Batt raced away from the Sheffield United backline before cutting a precise ball back across goal where Mooney was waiting unmarked.
He took his shot first time but it lacked the power needed to beat Long who managed to get across in enough time to make a comfortable save.
Having failed to score with two relatively simple chances by his high standards, Mooney tried an audacious long range chip when he spotted Long off his line just before the break, however he couldn't quite find the target meaning the sides finished the opening period all-square when the O's really should have been at least a goal to the good.
Both teams took a while to settle in after the restart, making it a much more balanced affair. Jose Baxter was looking more influential for the visitors as the game progressed, taking on a couple of snap shots, while Batt continued to terrorise the Blades' sluggish defence when he ran in behind.
But it was Sheffield United who took the lead on 67 minutes when Orient's defence failed to deal with a straightforward situation on the edge of their area. The ball ricocheted into the path of striker Chris Porter who calmly slid a pass to teammate Coady who was in acres of space inside the area and the Blades wide man slotted a low finish past Jones at the near post.
Orient brought on new loan signing Josh Wright immediately after going behind and this was soon followed by the introduction of Robbie Simpson in order to try and galvanise what had been a lacklustre second-half performance from the home side.
While the changes didn't have an instantaneous effect on Slade's men, they gradually and subtly began to edge themselves back into the game.
However there was nothing subtle about the O's equaliser with eight minutes to go. Substitute Wright was involved in the build up play but it was all about Orient number seven Cox who was 25 yards out from goal when the ball dropped out of the sky. The winger steadied himself before unleashing an unstoppable volley into the top left corner of the net, allowing Long no chance whatsoever.
Cox said his goal against Bristol City in midweek was one of the easiest he will ever score but this will surely rank amongst the best, even during a season that has brought a catalogue of memorable strikes.
It was going to have to be something special to beat the Blades goalkeeper who had been on form all afternoon and he was called into action again before the final whistle when he made a stunning one-handed save low to his left to deny Simpson who had sent a glancing header goalwards in stoppage time.
Orient couldn't find a winner before the final whistle despite continuing to pile on the pressure, but this will definitely go down as a vital point earned.
ORIENT: Jones, Cuthbert (Simpson, 73), Baudry, Clarke (C), Omozusi, Odubajo, James (Wright, 69), Vincelot (Bartley, 88), Cox, Batt, Mooney.
SUBS NOT USED: Larkins, Sawyer, Lasimant, Gorman.
GOALS: Cox (82)
BOOKINGS: Clarke (64), Vincelot (84)
SHEFF UTD: Long, White (Lappin, 73) , Maguire, Hill, Doyle (C), Porter (Taylor, 79), Baxter (Murphy, 85), McGinn, Collins, Coady, McMahon.
SUBS NOT USED: Howard, Miller, Cuvelier, King.
GOALS: Coady (67)
BOOKINGS: McMahon (6), Doyle (56), Maguire (75)
REFEREE: Darren Deadman
ATTENDANCE: 6,586 (1,128)