Stevenage suffered late heartache at The Abbey Stadium, as Harrison Dunk's injury time header sealed the points for Cambridge United.
The first half was a fairly drab affair, with few clear cut chances. Charlie Lee had the first after four minutes when his header hit the crossbar after good work from Steven Schumacher.
After a flat opening 20 minutes, Cambridge's first chance fell to Robbie Simpson, but his shot was saved by Jesse Joronen in the Stevenage goal after a defensive mix up between Schumacher and Mark Hughes.
Cambridge had the best of the play in the first half, with Liam Hughes' shot going over the bar after good play from Elliott Omozusi.
Cambridge then almost took the lead after a scramble in the penalty area, which Joronen saved. Leon Legge then headed just wide from the subsequent corner.
Joronen was a busy man throughout, having also saved Robbie Simpson's close range shot towards the end of the first half.
Boro struggled to create chances, with Charlie Lee and Tom Pett going the closest in the first half. Charlie Lee scuffed a shot wide after Ryan Johnson's long throw caused problems in the Cambridge area.
Lee was involved again moments later, picking up a misplaced pass to tee up Tom Pett, who had his shot deflected for a corner.
Stevenage finished the half missing another clear cut chance, after Charlie Lee's cross found the head of Tom Hitchcock, who could only head agonizingly past the post.
The second half saw an improvement for Stevenage, with Jack Jebb's shot sailing over the bar after good work from Tom Pett and Steven Schumacher.
Cambridge then took a foothold of the game, with the best of the chances falling to Luke Berry; his long range shot only just skimming the crossbar.
Dipo Akinyemi came on for Tom Hitchcock after 60 minutes, and his introduction helped the away side significantly. His cross found Charlie Lee, who could only backheel into the arms of Chris Dunn.
After Stevenage's strongest spell of the game, the home side began to dominate the closing stages of the game, carving out an array of chances.
Jesse Joronen made a point blank save from Harrison Dunk's header, after Ryan Johnson was controversially kept off of the pitch after an injury.
Robbie Simpson then blazed a shot over the bar by some distance, after a mazy run into the box from substitute Jordan Chiedozie.
Simpson kept causing problems for the Stevenage defence, with his fierce shot blocked well by Mark Hughes. From the subsequent corner, Simpson headed straight into the arms of Jesse Joronen.
Jordan Chiedozie then had Cambridge's best chance after 82 minutes, with his header floating agonizingly past the left hand post.
Simpson then had another chance, but his 25 yard drive went just wide of the Stevenage goal. Moments later, substitute Rory Gaffney's cross was headed just wide by Luke Berry.
Despite Cambridge's domination, Stevenage still carved out the best chance of the game, with Dipo Akinyemi agonisingly placing the ball the wrong side of the post.
That proved costly for Stevenage, as Cambridge continued to dominate, with Gaffney and Simpson both forcing Joronen into action.
The pressure finally told in the last minute of injury time, with Rory Gaffney's cross headed in by Harrison Dunk to deal the game's decisive blow.