Tranmere boss Ronnie Moore reckons his side need to win their last three games to have any hope at all of making the play-offs.
Tranmere slipped out of the top six over Easter and were dealt another blow as Championship-bound Doncaster completed a double over them.
There was little goalmouth action at either end before Doncaster skipper Rob Jones grabbed the all-important goal in the 63rd minute when he fired home after centre-back partner Jamie McCombe had headed down a free-kick from David Cotterill.
Moore said: "It's disappointing because it looks like a goalless draw all the game.
"I just couldn't see anybody scoring unless it was a 35-yarder or a piece of magic.
"But they got a free-kick and one centre-half heads it down to the other and bang - it's in the back of the net.
"They are a big, strong side and we had talked before the game about cutting down the corners and free-kicks we allowed them.
"It was the second ball that did us. When the ball was headed down our reaction was poor and that's been the case too often.
"It was a tight game and I can't fault our commitment, effort and desire, but one mistake by a defender has cost everybody."
Moore added: "I think we did well up to the final third, but we need to win our last three games now and to do that we need to start scoring goals."