Keith Andrews scored 29 seconds into the second half to give Ipswich victory over Derby, their first at Portman Road since mid-October.
Referee David Webb consulted his assistant before awarding the goal, having believed John Brayford had cleared Andrews' header off the line.
Arran Lee-Barrett twice denied Jamie Ward and saved from Craig Bryson in a busy first half for the Ipswich keeper.
And Town claimed victory when Andrews headed in Aaron Cresswell's cross.
The win helped Ipswich move five points clear of the relegation places, while for the Rams, it was their sixth defeat in their last eight games.
Lee-Barrett, who was thrust into the starting XI as loanee David Stockdale was recalled by Fulham following the injury to Mark Schwarzer, made several good saves in the first period.
At the other end, Andrews' long-range shot moved in the air and goalkeeper Frank Fielding had to push the ball away.
After Lee-Barrett made a fine double save to preserve Ipswich's clean sheet in the 27th minute, Andrews added to the two goals he scored twice against Barnsley last weekend.
Fielding flapped at the Republic of Ireland international's header before Brayford unsuccessfully tried to hack it clear.
The Tractor Boys could have extended their lead via Lee Martin, Ibrahima Sonko and substitute Jimmy Bullard in the second period, while the visitors scarcely threatened Lee-Barrett's goal to give the hosts a much-needed home win.