The substitute struck to secure a money spinning replay at the Emirates
A resilient first half display from the host's had offered the League One side hope, having held the Gunner's to 0-0, but it was dashed less than ten minutes after the restart with Tomas Rosicky meeting a superb Nicklas Bendtner cross to head past a helpless Jamie Jones in the Orient net.
However, the O's showed a superb resolve and when all had looked lost for the hosts, with only a minute remaining, substitute Jonathan Tehoue broke through to fire Russell Slade's side into a money-spinning replay at the Emirates.
Arsene Wenger had, unsurprisingly, made 10 changes to the starting line-up that had performed so effectively in the defeat of Barcelona on Wednesday evening, with Alex Song the only survivor from the clash at the Emirates and the Frenchman also offered a debut to Spanish defender Ignasi Miquel.
Orient's more modest resources would deem such squad rotation a near impossibility of course but Russell Slade did see fit to leave Tottenham loanee Harry Kane on the bench, with 37-year old Scott McGleish pairing up with Alex Revell up front.
The prize on offer to both teams was revealed merely 20 minutes before kick off, with the quarter final draw read out over the PA system at Brisbane Road. Manchester United at Old Trafford the spoils for the victors; a potential money-spinner for the hosts or another chapter in the Wenger/Ferguson history book if the Gunners were to progress.
If there wasn’t already enough Cup magic swirling around East London, the prospect of a trip to face United certainly ruled out any prospect of the clash being a damp squib.Orient made their intentions clear from the off, chasing down every ball with a tenacity befitting the occasion and their industry nearly supplied the hosts a dream start, with midfielder Stephen Dawson forcing a save out of Manuel Almunia within the first 57 seconds. Like their enigmatic chairman Barry Hearn, the League One were in no mood to shy away from the big occasion.
Arsenal, in contrast, were displaying a languidity that suggested that they had yet woken up from their dream fixture against Barcelona on Wednesday evening, with sloppy touches and for all of their possession in the opening 10 minutes, there was very little to suggest that Orient were in immediate danger of collapsing in the face of their illustrious hosts.
However, Marouane Chamakh offered a timely reminder on the 12th minute that Russell Slade's side would need to keep up their magnificent early pace for longer than the opening exchanges, with the Moroccan wasting a fine chance in Jamie Jones' box. It was a strike typical of a striker looking particularly low on confidence.
Low on confidence, Orient were not and the deadlock was nearly broken by, of all people, a former Spurs player for the hosts, as Charlie Daniels lashed a fantastically struck effort from 25-yards out only to see it rise marginally above Manuel Almunia's bar. The threat of Arsenal was apparent on the counter attack, with Alex Song particularly looking to move forward but the gulf in class was less so as the game reached the 25 minute mark.
The Gunners were receiving a taste of the medicine they gave to Barcelona on Wednesday night, with Russell Slade having instructed his team to harrass the Premier League side in the middle of the park, offering them no room to breathe and no room to create as a unit.
Individual beauty is difficult to suppress however and Andrey Arshavin was finding chinks in Orient's robust armour, testing Jamie Jones from outside of the box and teasing in the final third but the Russian alone wasn't a threat powerful enough to breach the host's resilience. Arsene Wenger's side were keeping the ball with typical elegance but possession wasn't proving profitable as the half hour mark passed.
It would be unfair to label the clash a meeting of brain and brawn but Arsenal's inability to to deal with Orient's physicality was only matched by their growing number of well worked, metronomic pass and move in the centre of the Brisbane Road pitch. Ten minutes before half-time, the visitors briefly shot through the gears and it nearly payed dividends as Kieran Gibbs, who had looked a threat down the left flank, layed a perfect ball for Chamakh to convert but the former Bordeaux man fluffed his lines, slicing his effort well wide.
It was very much a let off for Orient but as the half-time whistle went, it would be difficult to begrudge the hosts what was quite literally a slice of luck.
It was much of the same as the second half restarted, with Tottenham loanee Tom Carroll having come on for the injured Jason Crowe and despite having lots of the ball, Arsene Wenger's side were very much going through the motions, in complete contrast to not only the club's defeat of Barcelona but also the performance of their hosts.
However, as the home fans at Brisbane Road will have surely feared, Arsenal's dominance of possession told and it was Tomas Rosicky, having looked a little uninterested throughout, who broke the deadlock, meeting a fine Nicklas Bendtner cross to head the Gunners into a deserved and somewhat inevitable lead.
The goal forced a response from Russell Slade's side and the game became stretched, with gaps opening up ominously at both ends of the pitch as the hour mark approached. Though the hosts looked in no way that they were likely to collapse and the Czech international's opener appeared to prove the catalyst for the home side, who were refusing to wilt, with Alex Revell in particular proving to be a thorn in the Arsenal defence's collective side.
For all of Orient's will, fatigue was becoming evermore apparent and the home side's heavy legs were looking likely to become a decisive burden and Arsenal were looking to kill off the tie with some wonderful possession football down the left hand side. With just over 20 minutes remaining, they nearly did just that with Rosicky again forcing two fine saves out of Jamie Jones.
The O's were showing typical heart and the equaliser was very nearly on after substitute Jonathan Tehoue motored down the right to set up Alex Revell on the edge of Manuel Almunia's box but the chance was wasted and Leyton Orient's opportunities were dwindling in the face of Arsenal's long periods of possession.
Tehoue's introduction was causing the Gunners a number of problems down the flanks and his pace very nearly opened up Arsene Wenger's side with just less than ten minutes remaining, setting up Alex Revell once again only for the striker to see his effort smash into the face of Sebastien Squillaci. There were calls from the Brisbane Road for a handball but they were very much out of hope rather than expectation. Orient had definitely not given up on the equaliser as the final whistle approached.
Their attitude was to prove decisive as the inspirational substitute Jonathan Tehoue jinked between Kieran Gibbs and Ignasi Miquel to smash home a fine low effort past Manuel Almunia to fire Brisbane Road into raptures and Russell Slade's side into a priceless replay at the Emirates.