The Blues returned from Ireland on Monday morning and a similar squad, without Pablo Counago and Ben Thatcher, travels to Roots Hall.
Keane is expecting an improved display from a side that suffered a 2-0 defeat at Cork on Sunday.
"We started off a bit sluggish and players weren't holding the ball up and that made it a long 90 minutes," he told the club's offical website.
"The performance wasn't good enough but I try not to over-analyse pre-season as I've been involved with teams that have been flying but then it doesn't happen and vice-versa.
"Over the next few games though we will be nailing things down in terms of team shape and players will fall by the wayside."