March struck twice as the Seagulls made it three successive friendly wins with a commanding performance at Roots Hall. Glenn Murray also netted as Albion gave a debut to Izzy Brown, who joined on a season-long loan from Chelsea earlier in the day.
In the opening two matches against Fortuna Dusseldorf and Crawley, Albion players were given 45 minutes but the majority played at least an hour tonight, with the bench comprising youth and fringe players.
On a tricky surface, with slightly long grass, Southend winger Michael Kightly tried to catch out Albion stopper Niki Maenpaa with a free kick from a tight angle early on but his effort flew into the side netting.
Albion's first chance fell to Pascal Gross, who fired straight at Ted Smith from 22 yards on 14 minutes, before Marc-Antoine Fortune was denied by Maenpaa diving low to his right at the other end shortly afterwards.
The Seagulls looked lively going forward and Steve Sidwell was denied by Smith after a neat one-two with Gross, before Glenn Murray had a strong shout for a penalty waved away as he went down under a Jason Demetriou challenge.
Albion's strong period of play was rewarded when they took the lead on 34 mintues. Liam Rosenior crossed from the right and March took a touch and emphatically volleyed home to score for the second successive friendly.
Gross almost added a quick second but could not get enough on a low Rosenior centre but it was not long until Brighton did go 2-0 ahead. March was given too much space on the edge of the penalty area and drove a low shot into the far corner from 20 yards on 42 minutes.
There was still time for Albion to add a third before the break as Dale Stephens fed Markus Suttner out wide and he delivered a delicious cross which Murray headed home from close range.
The second half was a quieter affair with few chances as both teams made a host of changes.
The hosts' Fortune blazed wildly into the fans behind Maenpaa's goal on the hour, while Albion substitute James TIlley fired against the legs of Smith from Ben White's cut-back late on.
BRIGHTON: Maenpaa; Rosenior (White 62), Hunemeier, Dunk (Dallison 82), Suttner (Cox 62); March (Tilley 82), Stephens (Molumby 82), Sidwell (Ince 62), Brown (LuaLua 62); Gross (Towell 82); Murray (Connelly 71). Subs: Sanchez, Hutchinson, Collar.
Att: 3,353 (270 Albion fans).
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