Debutant Aaron Doran scored his first professional goal as MK Dons eased past a lacklustre Southend 2-0 and into the quarter-final of the Johnstone's Paint Trophy.
The on-loan Blackburn winger, 18, set the Dons on their way with a cool finish before Mark Carrington made the game safe on the stroke of half-time.
Leyton Orient edged past Brighton 1-0 with an 88th-minute goal from striker Adrian Patulea.
The Romanian frontman latched on to a knock-on from substitute James Scowcroft to fire past Brighton keeper Graeme Smith.
Southampton goalkeeper Kelvin Davis made up for two first-half blunders with a penalty save to guide his team through to the next round thanks to a 5-3 shootout win over Torquay following their 2-2 draw.
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