Macaulay Langstaff's 28th league goal of the season worsened Colchester's relegation fears as they lost 1-0 to Notts County.
The visitors almost took the lead early on when Ellis Iandolo's speculative effort from distance almost caught Luca Ashby-Hammond off guard, the keeper tipping the ball onto the woodwork.
It was the Colchester full-back involved once again minutes later, producing a last-ditch tackle to deny Langstaff an opportunity to shoot inside the area.
Jodi Jones saw his effort clip off the crossbar, with Cameron McGeehan found unmarked inside the box at the other end but heading straight at Ashby-Hammond.
The hosts continued to create the better chances, as Crowley saw his effort blocked on the line by Riley Harbottle seven minutes after the restart.
But County's pressure would pay two minutes later when good work between Aaron Nemane and Crowley was finished off by Langstaff, putting the ball in off the crossbar.
Harbottle almost secured the away side a point late on as his header came off the post, with Colchester now three points ahead of relegation rivals Sutton who conceded a late equaliser to Crawley.