Substitute Paul Hayes' goal secured Preston a point at Doncaster, but hopes of a great escape for Phil Brown's men are fading.
Doncaster led when Simon Gillet's clever pass picked out Brian Stock to score from the edge of the box.
Hayes then nodded in the equaliser after Bongani Khumalo's shot had hit the bar.
Preston remain second bottom, seven points off safety, while Rovers stay two places above the drop zone.
The result does more favours for Sean O'Driscoll's Rovers, who halted a run of three straight defeats and sit eight points clear of the relegation places.
Both sides enjoyed a host of chances in an entertaining, end-to-end affair at the Keepmoat Stadium.
Doncaster almost had the perfect start when Stock's perfectly-measured first-time pass found left-back George Friend in the area. Friend let fly with a rasping effort that had Preston goalkeeper Iain Turner at full-stretch to beat over the bar.
The game developed a cat-and-mouse feel as Preston worked tirelessly to thwart Doncaster whilst still posing a threat on the counter-attack.
When Iain Hume and Keith Treacy combined in the 35th minute, North End should have gone in front. Treacy's goal-bound volley from Hume's left-wing cross was spilt by Woods to leave Johnson with a golden opportunity, but Preston's on-loan Fulham forward thumped into the side netting from point-blank range.
Rovers came close when James O'Connor's teasing 70th-minute cross skimmed off Nicholson's head, forcing Turner into a splendid reaction save and the Rovers right-back was immediately involved in another flashpoint at the other end when Hume played in Johnson.
Although O'Connor's contact with the American appeared to be minimal, Preston's players furiously surrounded referee Scott Mathieson when a penalty was not awarded.
Doncaster pressed once more, Franck Moussa's exquisite 25-yard volley cannoned back off the underside of the crossbar. And then, Simon Gillett's smart cut-back caught out the massed ranks of Preston defenders and left Stock free to rifle into the top corner from the edge of the box.
Preston immediately sent on Hayes for Johnson and the former Scunthorpe man snatched a quick-fire equaliser.
When Bongani Khumalo shot against the crossbar it was Hayes who was on hand to bravely nod home the rebound from a tight angle.