Saints suffered a fright on All Hallowes' Eve before coming back from two goals down to earn a draw at Brisbane Road.
Two goals inside the last twenty minutes of play from Rickie Lambert forced a draw in East London after an enthralling game which either side might have won.
Saints controlled much of the play, but they had to battle back and the spirit shown by Alan Pardew's side was just reward for the 3,000 fans who had travelled up from the south coast.
Leyton Orient: Morris, Purches, Chorley, Mkandawire (Ashworth 4), Melligan, McGleish (Scowcroft 71), Daniels, Summerfield, Smith, Patulea (Jarvis 79), Townsend. Subs (not used): Butcher, Demetriou, Cave-Brown, Pires.
Saints: Davis, James, Jaidi, Trotman, Harding, Wotton (Connolly 55), Hammond, Schneiderlin, Lallana, Waigo (Antonio 63), Lambert. Subs (not used): Bialkowski, Thomas, Perry, Mills, Mellis.
Referee: Mr. Linington
Attendance: 7,544 (including 3,208 away)
Saints lined up in their changed strip of blue and yellow as the hosts got things underway at Brisbane Road.
Orient took the lead from the first attack of the game. A cross from winger JJ Melligan was met by defender Tamika Mkandawire who found the top corner with a fortuitous looking header as he clashed with Neal Trotman in the process.
The header had just enough on it to find the top corner, escaping the clutches of 'keeper Kelvin Davis. It was, however, to be the last action of the game for the goal scorer, as the collision of heads meant that Mkandawire had to be replaced by Luke Ashworth. Trotman meanwhile, was OK to carry on.
Backed by a large and vociferous traveling support on one side of the ground which created a home tie feel to the game, saw Saints respond by putting the pressure on at the other end with a flurry of efforts, but they couldn't get a clear sight of Glenn Morris' goal.
Adam Lallana benefited from a Rickie Lambert knock down, but couldn't get a clean strike on his shot inside the area.
Lambert then struck a long range effort wide before Saints won a succession of corners, the closest of which came from Lloyd James on the right, which Hammond headed across goal, but play was pulled back for an earlier infringement.
The hosts, who had been quiet since the goal almost doubled their advantage from a corner just past the half hour mark. Defender Ben Chorley hit his shot into the ground and the ball went over, failing to trouble Davis.
Alan Pardew's side continued to create opportunities on either flank, with Lloyd James required for corner duty on several more occasions as Papa Waigo and Dan Harding were industrious going forward.
In the 39th minute Saints went the closest they had come so far to a goal. A firmly struck free-kick from Lambert hit Chorley and rebounded out to Wotton. The midfielder's low shot fell to Lallana, but the Academy graduate couldn't guide the ball past Morris from close range.
Two minutes before the break, James' pass down the left side found Waigo and the Senegalese forward picked out Lambert, but the striker screwed his first time shot narrowly wide.
Saints' first half frustrations were summed up in the second minute of added on time, as Charlie Daniels' back flick deep inside the Orient half deflected off James and went out for a goal kick.
Half Time: Leyton Orient 1-0 Saints
The visitors started the second half brightly and set about testing the O's backline straightaway. Lambert's cross from the right was met by the head of Lallana, but the youngster's effort was saved by Morris, who then blocked a follow up from Papa Waigo.
Five minutes later Hammond headed over from Harding's cross on the left and then Schneiderlin was denied by Morris as he went through on goal.
From the resulting clearance, Andros Townsend's cross from the left bounced up inside the Saints area and flew past Davis off Neal Trotman for an unfortunate own goal against the run of play which made it 2-0.
Alan Pardew responded by bringing on David Connolly for Paul Wotton as Saints pushed further forward.
A pulsating move moments later, saw Schneiderlin and Lallana go close to putting Saints back into the game. The latter's effort came off the back of a neat cross from Lambert but went wide of the far post.
Some more resolute defending from Geraint Williams' side continued to thwart Saints as Connolly tried to make his mark on the game with two efforts inside the area which went over.
Saints fans did their bit to try and encourage a goal as a beach ball temporarily entered the field of play, but this one didn't appear to have come from Liverpool.
Luke Summerfield was alert to clear Radhi Jaidi's header off the line as a Saints breakthrough still looked like it wouldn't come.
It did finally arrive in the next attack. Lallana picked out Lambert in the middle of the area, and the forward's well executed first time finish from seven yards out in the 74th minute got the visitors back into the game at 2-1.
Inside the last ten minutes Hammond's cross towards the far post narrowly avoided the head of Connolly as the visitors piled on the pressure.
The equaliser which had looked on the cards came on 83 minutes as Lambert smashed a high first time shot into the top right hand corner sparking wild celebration from Saints fans.
It looked as though there could only be one winner from there as the visitors chased a replication of a memorable comeback at Preston which was achieved almost a year ago to the day. Connolly was the next to go close and Lambert sought a hat-trick but neither could force a way through.
A grand stand end to the game ensued as four minutes were added on. Substitute Ryan Jarvis almost put a sting in the tail of the game as he sent in a devilish looking cross which flew wide of Davis' far post, but a stalemate was the final outcome at Brisbane Road.
Full Time: Leyton Orient 2-2 Saints
