Dean Smith's men then grabbed one on the counter attack in the thick of a spell of U's pressure after the interval, to condemn Colchester to an eighth home defeat from twelve.
A bright start was undone by the visitors' first, and then the U's hit the bar in the second half as Alex Wynter headed against the woodwork from close range.
The Saddlers were able to take their two chances, whilst the U's will look back at their own opportunities to get something out of the match.
It was an all too familiar tale for Colchester United on Saturday afternoon, as they were defeated by Walsall at the Weston Homes Community Stadium.
An impressive away win at Peterborough last week gave U's the perfect start to 2015, but this time they were up against a Walsall side that was unbeaten in their last six away games.
During the attack Watt had juggled the ball through the box and in doing so, caught James O’Connor on the head, the defender would play no further part and was replaced by Paul Downing.
Sammie Szmodics has made a real impression during his recent run in the first team and was next to get a chance on goal when the beat offside trap, but one on one with O’Donnell he was denied.
A mix up between keeper and defender almost cost Walsall when Healey stole the ball away from Andy Taylor’s back pass, but on the turn and leaning back he scuffed his shot.
The early Colchester pressure was telling but on the half hour mark Walsall got into the game, first coming close through Jordan Cook who cut in from the left and powered a shot off of the outside of the post.
Minutes later Cook again out left opted for this cross which was met by Forde deep inside U’s box, he neatly headed home giving the Saddlers a one goal lead.
The goal didn’t hinder U’s effort and they were back in front of goal soon after, tenacious work from George Moncur led him into the box but with men between him and goal he curled his shot wide.
David Fox found a bit of space out wide right and launched a low bouncing shot, a deflection took the ball out for a corner but O’Donnell watched nervously as it whisked just wide of the far post.
The resulting corner saw another chance for Szmodics as Moncur brought the ball down and laid it off for him, his low shot again denied by a block, leaving U’s a goal down going into the break.
Elliott Hewitt had a decent opportunity early in the second half, with the ball bouncing up in front of him he opted for the spectacular half volley but couldn’t quite get the connection.
That man Szmodics popped up in the box again, this time he received the ball flicking it up to set himself for a half volley but fired just over the bar.
The home side continued to pressure and had the fans on their feet with the next chance as the ball all but crossed the line.
Kaspars Gorkss found himself in a different position but regardless sent in a cross which Wynter headed onto the underside of the cross bar, a scramble for the rebound saw the Saddlers clear the danger.
Again Szmodics’ hard work and persistence was on show as he latched onto a loose ball and once within a sight of goal clipped a low shot, O’Donnell was on hand to again deny the youngster a goal.
Healey had led the line well for Colchester in Sears’ absence, but with twenty minutes to go he was replaced by Macauley Bonne, who was soon followed by Gavin Massey replacing Watt on the left.
However as the U’s pushed on they were left open to the counter and counter Walsall did. Saddlers’ top scorer Tom Bradshaw squared the ball to Cain and he calmly slotted home to double the lead.
Humes made his last move of the game which saw Hewitt replaced by Dion Sembie-Ferris who had previously impressed coming off the bench at Cardiff, this was his home debut.
Colchester still had some fight left in them despite the goal margin, Moncur made good progress through the Walsall half before stabbing a shot on goal, O’Donnell there again to save.