The victors will be guaranteed a place at Wembley Stadium in the final of the competition, with the away side just shading the betting with Bet Victor at 8/5 (2.60).
It is a close call though, with Southend available at a price of 15/8 (2.88) to win on home soil while the draw is at 9/4 (3.25).
These odds suggest the match is pretty much up for grabs, despite Southend holding on in the first leg to secure an advantage as the underdogs from League Two.
But Orient were unfortunate not to score in that game, and could come back stronger at Roots Hall for the defeat.
Southend have lost their last two home games - curiously by the same 2-1 scoreline - while the visitors have also had a 2-1 result in their last two matches. The most recent was a defeat at Hartlepool, while the other was a victory at Tranmere.
Perhaps it would be foolish to expect another 2-1 scoreline, but it looks like a reasonable outcome in this game and at odds of 17/2 (9.50) is worth a punt in favour of the travelling Leyton Orient.
More cautious punters will perhaps prefer to back shorter odds with more chance of a return, and that can be found at 5/6 (1.83) for Russell Slade's side to win in the draw no bet market.
Orient will feel the more confident side going into the game despite Southend's advantage because their squad is far closer to full-strength than the Shrimpers, who have a number of players out injured.
|Back Leyton Orient to win (draw no bet) at 5/6 (1.83) with BetVictor
||Leyton Orient to win 2-1 at 17/2 (9.50) with BetVictor|
Jamie Dickenson is a 22-year-old freelance journalist who specialises in football, sports and betting.
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