Orient battled to a dramatic late win over Port Vale to ensure they remain two points clear at the top of League One, extending their historic 100% start to the season to six games.
The O's were made to work for their win having gone behind to a first half header from Louis Dodds - the first time they have fallen behind in the league this season. But David Mooney responded with his sixth and seventh goals of the campaign to give his side a well-deserved lead at half-time.
However the visitors forced their way back into the game in the second period, with Jennison Myrie-Williams equalising soon after half-time. And it looked as though the O's were destined to drop their first points of the season, only for Kevin Lisbie to keep his nerve in the dying moments of the game and snatch a 3-2 win for Russell Slade's men.
It was Orient's first league game this month after last week's fixture against Notts County was re-scheduled for Tuesday 17th September due to the international break.
And O's boss Slade made four changes to the side that was victorious over Gillingham in the first round of the Johnstone's Paint Trophy; Johnny Gorman, Marvin Bartley, Jayden Stockley and hat-trick hero Shaun Batt making way for Scott Cuthbert, Dean Cox, Mooney and Lisbie.
In the opposite dugout, Micky Adams made two changes to the Port Vale side that beat Carlisle 1-0 away from home last week, replacing Chris Birchall and Ben Williamson with Myrie-Williams and Kaid Mohamed.
And it was these two - playing at right and left midfield respectively - who contributed most heavily to a lively start from the away side, putting O's full-backs Elliot Omozusi and Scott Cuthbert under plenty of pressure.
But the league leaders did not take long to begin exploiting the flanks themselves, having claims for a penalty waved away by referee Mike Russell just before the 10 minute mark when Mooney's pass was latched onto by Moses Odubajo who appeared to be muscled off the ball by Vale defender Carl Dickinson in the box.
Five minutes later, Mooney brought the best out of the visiting keeper when he turned well on the edge of the area and sent a curling shot towards the top left-hand corner only for Chris Neal to tip the ball over in spectacular fashion.
Orient were beginning to take a hold of the game but, on 21 minutes, found themselves behind in the league for the first time all season.
Myrie-Williams' deep corner was played back into the box by Port Vale and Jones was only able to get a slight touch on the cross allowing Louis Dodds to nod the ball home.
But just two minutes later the home side fought their way back onto level terms. A ball swung in from the right by Lloyd James was brilliantly chested down by Lisbie on the edge of the box straight into the path of Mooney who hit a thunderous first time effort into the top left corner of the net, this time giving Neal no chance to react.
The referee had to consult his assistant to check that Mooney hadn't strayed offside before allowing the goal and the 30 seconds of hesitation only added to the celebrations from O's fans and players alike once the goal was given.
Shortly after equalising, neat interplay down the right flank involving Odubajo and Cox caused panic in the Vale area before Anthony Griffith managed to head behind. The O's were unable to capitalise on the resulting corner but they were now in the ascendancy while their opponents looked nervy both in possession and when faced with Orient's increasingly frequent surges forward.
However Vale's apprehension turned to frustration on 38 minutes when Liam Chilvers and Dickinson simultaneously flew into a tackle on Odubajo who had sped away from both of them deep inside the visitors half, with both defenders receiving a yellow card for their challenges.
Minutes later, Odubajo managed to sneak in behind Vale's backline again and got himself on the end of a tidy ball over the top from Cox, however the wide man couldn't find the target once the ball dropped for him on the edge of the six-yard box.
Orient had dominated the game from the minute they grabbed the equaliser but they did not allow themselves to become frustrated at the fact they had not managed to turn their dominance into another goal, remaining patient with the ball and disciplined off it.
And this attitude paid off when they took the lead in first half stoppage time. Superb pressing from Romain Vincelot - who narrowly missed out on the player of the League One Player of the Month award recently - forced Vale defender Chris Robertson to concede possession when he was the last man in defence.
Rather than shooting himself, Vincelot opted to unselfishly play a chipped ball to Mooney at the far post and the striker made no mistake in front of goal, firing past Neal to claim his seventh of the season and send his side into half-time with a deserved 2-1 lead.
As with the opening half, Port Vale made a more energetic start to the second period and had the first sight of goal when Tom Pope sent a header into Jones's side netting.
But from the resulting O's' goalkick, Cox picked it up the loose ball and played it inside to Lisbie, who was 25 yards from goal, and his well struck drive needed a strong hand from Neal to keep it out.
Cox was looking particularly energetic and dangerous as he started to drift infield from the left flank more and more, and presented Lisbie with another chance when he scooped a skilfull ball over the Vale defence onto the head of the O's number nine but Neal dealt well with the striker's looping effort.
Despite Orient continuing to look the more dangerous side, Port Vale found themselves on level terms on 53 minutes.
Doug Loft's deep cross from the left was parried away by Jones but only as far as Myrie-Williams who directed an accurate header into the bottom left corner.
The equalising goal immediately spurred on Slade's men and they enjoyed a lengthy spell of pressure, during which Cox saw another effort cut out by the opposition defence having been put through on goal by a neat pass from Mooney.
However the O's boss sensed they needed something fresh to give the Vale defence something to think about and, with 68 minutes on the clock, decided to replace Cuthbert with Batt, who notched a hat-trick in the Johnstone's Paint Trophy game at Gillingham 11 days ago.
And within minutes of coming on he was causing the opposition all sorts of problems - first of all forcing Neal into a decent save having shot first time from the edge of the area, before driving inside and setting up Cox who was denied by another good block from the Vale defence.
However, unable to find a breakthrough, the O's were allowing themselves to become frustrated, demonstrated none more so than by the three yellow cards picked up by James, Baudry and Omozusi within the space of six minutes.
In turn, this allowed Port Vale to gain some momentum and they very nearly took the lead 15 minutes from time when Myrie-Williams curled a brilliant free-kick goalwards, striking Jones's crossbar before being scrambled away to safety.
This was soon followed by a driving run from Mohamed through the middle, and his ferocious shot from 25 yards flew just wide of Jones's left hand post.
Slade was urging his players to lift themselves from the touchline for one last push with the game wearing on and the visitors continuing to threaten every time they came forward, certainly looking the most likely to score.
But with just two minutes left, Orient broke away after a heavy spell of sustained Vale pressure and Lisbie somehow managed to slalom his way through the visitors defence before firing an emphatic finish past Neal.
The tension as he entered the area and before he unleashed his shot could be felt all around the ground, but the sight of the ball nestling in the back of the Port Vale net sent the crowd wild.
Despite the late goal, the game still had a long way to go with the fourth official signalling that there would be five minutes of added time.
The visitors piled on the pressure, sending a series of high balls into the O's box however Jones dealt brilliantly with each and every one, reassuring his teammates that their 100% start to the season was going to remain well and truly intact.
See the goals and stats below...
ORIENT: Jones, Omozusi, Clarke (C), Baudry, Cuthbert (Batt 68), Cox, James (Bartley 75), Vincelot, Odubjo, Mooney, Lisbie (Stockley 90).
SUBS: Larkins, Lasimant, Gorman, Lee.
GOALS: Mooney (23, 45+2), Lisbie (88)
BOOKINGS: James (72), Baudry (76), Omozusi (78)
VALE: Neal, Robertson, Dickinson, Chilvers, Loft (C), Dodds (Williamson, 75), Myrie-Williams, Pope, Griffith, Mohamed, Duffy.
SUBS: Yates, Tomlin, Shuker, Lines, Birchall, Hughes.
GOALS: Dodds (21), Myrie-Williams (53)
BOOKINGS: Dickinson (38), Chilvers (38), Pope (64) Robertson
ATTENDANCE: 4,888 (438)
REFEREE: Mick Russell