Outstanding display earns a point, with a win now a must on Sunday.
And yet they couldn't quite find that second goal their efforts more than deserved and it's all down to a final day showdown with Preston, with both teams having all to play for.
The performance was one of the most impressive this season and the U's were denied by both the inside of the post and the linesman's flag as they pinned Swindon in, in the second half.
The team gave their absolute all on a dramatic night at the Weston Homes Community Stadium on Tuesday night, urged on by a buoyant and passionate home support.
Colchester United will need to win on the final day of the season to ensure League One football next season.The U’s got off to a dream start, taking the lead within the first couple of minutes. Massey got to the touchline and cut it back for Murphy to ghost in and tap home to send the home fans into raptures.
They almost made it 2-0 shortly afterwards, as Gilbey found space on the edge of the box before drilling just over the bar.
And then it was goal provider Massey who nearly turned goalscorer as he wriggled past two in the box to shoot past the far post.
Swindon were happy to hit on the break and they perhaps should have done better after twelve minutes when a cross from the right was missed by Williams at the far post.
Moncur then went close on the 17 minute mark, drilling a shot just over the bar as it broke to him on the edge of the box.
At the other end, Khumalo got a foot in just at the right time as Swindon broke the offside trap and were two on one with the big South African.
The U’s kept creating chances though and a cross to the far post by Massey was headed just over the bar by Gilbey.
Gladwin fired a long distance free kick over the bar for the visitors, before Thompson, who was giving Briggs all sorts of trouble, forced Walker into a great reflex save.
The U’s had had to weather a storm, but with eight minutes left of the half, Murphy won another corner in his battle with his full back. From the set piece, Porter won a clean header, but it was well saved by Foderingham.
Murphy then drove down the left to drop it back to Moncur, but he scuffed his shot and it was well blocked.
At the other end, Swindon worked a good position, but Walker pulled off a sensational stop to ensure the U’s were ahead at the break.
The U’s nearly doubled their advantage just after half time as a Murphy driven cross was deflected. Foderingham reacted to palm it into the air and Stephens cleared off the line.
Byrne was the most dangerous player on the pitch, though and caused problems for the U’s early in the second half.
And from a corner won by some of his trickery, Gladwin rose highest to head home past Walker.
At the other end, Massey drove up the pitch and pulled a shot just wide of the post with Foderingham scrambling across his goal.
Then, at the other end, Hylton somehow managed to burst through but, with only Walker to beat, stabbed his shot wide.
Luongo forced a good save out of Walker before, at the other end, Moncur shot just over the bar after Gilbey was felled just outside the box.
With fifteen to go, Briggs sprung down the left and set up Moncur, but again he was unable to beat the keeper with his effort.
Next, Porter wrestled the ball off his man and drove a shot straight into the stomach of Foderingham.
Dion Sembie-Ferris was the U’s first sub, replacing the tiring Murphy, and made an instant impression, driving towards goal and setting up Moncur.
The midfielder smashed home, but was cut short in his celebrations by the linesman’s flag.
They went close again with eight minutes to go as Fox sent over a cross to the far post. Porter’s header beat Foderingham, hit the inside of the post and stayed out.
Next, the U’s big front man curled one just past the upright, before Walker had to pull off two or three great stops to deny the Robins.
In the five minutes injury time, the U's kept trying to find a way through, but they just couldn't find that lucky moment that would have seen them home.
Onto Preston and both team's day of destiny.