The Gills Ladies exit the FA Womens Cup in the Second Round against their Essex rivals at Heybridge Swifts.
The U's started off brightly and forced Gills goalkeeper Alison Smith into a fine save within the first 90 seconds.
The Gills had their first chance in the third minute when a lovely through ball found Leanne Stevens but the central midfielder could only fire straight at the Colchester keeper.
Smith was again in action in the sixth minute, saving well from
Colchester's number 10 and the ball being cleared by centre-half Kelly Seath.
First blood went to the Gills in the 12th minute when Anna Broad's flick-on found Gina Payne. The striker rounded the Colchester keeper, who tripped the Gills number 8, but the ball rolled into the empty net to break the deadlock.
The lead lasted for a minute as Colchester's number 2 scored after good work from the number 10.
Five minutes later and the U's took the lead. A penalty area scrambles saw the Colchester number 9 pick up on a loose ball and fire past Smith.
The Gills pushed forward for an equaliser but fell further behind when the Colchester number 6 headed home from a corner.
The second-half saw the Gills start brightly and they pulled a goal back in the 47th minute when Les Kaye's through ball reached Payne and the striker fire home her second goal of the game.
Manager Hugo Langton replaced Kirsty Goodall with Terri Reynolds in the 58th minute.
A disputed offside decision in the 67th minute for the fourth Colchester goal knocked the wind out of the Gills Ladies sails. A ball over the top of the Gills defence fell to the U's number 9, who was several yards offside, and she rounded Smith and scored her second goal.
A miskick from Smith in the 75th minute saw the Colchester number 9 score her hat-trick when she slotted home at the near post.
Gemma Ridge replaced Whitney Judd in the 77th minute.
The final Gills substitution saw Nicola McCormack replace Seath.
The U's extended their lead in the 84th minute when their number 15 picked up a loose ball and fired home.
Colchester wrapped up the win in the last minute when a bit of up-and-under found the 15 and she slotted past Smith.
Gills: Alison Smith, Becky Lyon (C), Kelly Seath (Nicola McCormack 81), Jac Fiddyment, Whitney Judd (Gemma Ridge 77), Kirsty Woolard, Les Kaye, Leanne Stevens, Anna Broad, Gina Payne, Kirsty Goodall (Terri Reynolds 58).
Gills Ladies Manager Hugo Langton was disappointed with the officiating that saw his side exit the FA Womens Cup: "
I was livid with the way the game changed. We pulled it back to 3-2 and were in the ascendancy. There was only one team in it and if anyone was going to score again, it was us.
"I don't want to go over the top and I don't want to have a go at officials, as they have a tough job to do, but the fact of the matter is some poor decisions cost us, especially their fourth goal, as it was blatantly offside.
"Colchester are a very good team and we were giving them a real game, and the fourth goal knocked us sideways. Colchester's manager is a good guy and I wish his team all the best in the next round."
Match Report by James Case.
