Rickie Lambert scored one and laid on another as Southampton beat Leyton Orient to go second in League One.
Lambert gave the Saints the lead when he rose highest to head Ryan Dickson's left-wing cross home.
Jimmy Smith had two efforts ruled out for offside for the hosts while Kelvin Davis did well to deny Scott McGleish.
Lee Barnard settled any of the visiting supporters' nerves when he slotted home Lambert's pass, while Stephen Dawson struck a post late on for the Os.
Southampton took advantage of Huddersfield's draw with Peterborough to take the second automatic promotion slot, and also enjoy two games in hand over those below them.
Leyton Orient's play-off push took another denting and they now sit three points off 6th-placed Bournemouth, albeit with a game in hand.
Leyton Orient boss Russell Slade told BBC London 94.9:"I thought the better team lost today by a mile to be honest. I thought we dominated proceedings in the second period but without getting a goal.
"We won't give up and you saw that today. We'll give everything in our quest to be successful. That is what I demand, and the response I got at half-time was magnificent."
Southampton boss Nigel Adkins told BBC Radio Solent:"We've come away to a very difficult place, it was an excellent victory for us.
"The supporters were maginificent, the players showed great character against a team who are doing very, very well.
"We're in a situation now where we just have to keep driving everyone on."