Morecambe secured their 18th draw of the season with a point taking them five points clear of the bottom two with two games to go in League 2.
A share of the spoils moved them up to 21st in the table and needing a point from their last two games to ensure safety.
The Shrimps made two changes from the side beaten at Crewe Alexandra on Saturday with Adam Campbell and Kevin Ellison replacing Andy Fleming and Garry Thompson.
They started well with Callum Lang looking a threat going forward. He had a shot deflected behind inside two minutes and, from the resulting corner, Cambridge failed to clear with Sam Lavelle ultimately heading over.
Seven minutes later and Lang threatened again as he ran on to Campbell’s through ball but saw his shot well saved by Cambridge’s debutant keeper Dimitar Mitov.
The visitors played some neat football without posing much in the way of a threat to the home side.
George Maris had their only effort of the first half, a first-time effort from 20 yards that was comfortably held by Barry Roche.
At the other end Lang saw another shot go off target and a Campbell free-kick was cleared with Steve Old well placed as the first half came to a conclusion. Morecambe raised their tempo after the break with Lang still their likeliest source of a goal.
The second half was barely a minute old when Campbell released Lang into the area for a corner which came to nothing. With one goal increasingly looking like deciding the match, Cambridge won three consecutive corners after Jevani Brown’s shot was deflected narrowly wide.
The last of those saw Uche Ikpeazu turn and shoot wide of Roche’s left-hand post as proceedings became increasingly tense. Ellison could have calmed the home fans’ nerves but made a mess of Campbell’s cross when six yards out. Maris curled another long-range attempt off target and Mitov parried Aaron McGowan’s shot with the loose ball falling to a Cambridge defender.
The game opened up in the final 10 minutes and Cambridge almost snatched victory in the final stages. Jake Carroll shot wide and Harrison Dunk hit the side netting before a goalmouth scramble ended with Alex Kenyon producing a vital goal line clearance to ensure both sides shared the spoils.
Morecambe: Roche, McGowan, Lavelle, Old, Conlan, Kenyon, Rose, Campbell (Wylde 76), Lang, Ellison, McGurk. Subs not used: Nizic, Fleming, Oliver, Wildig, Lund, Muller.
Cambridge United: Mitov, Halliday, Taylor, Taft, Carroll, Amoo (Waters 76), Deegan, Maris, Dunk, Amoo, Brown. Subs not used: Iron, Legge, Elito, Lewis. Referee: Ross Joyce.