Fred Onyedinma struck early in the second half as bottom club Wycombe won for only the seventh time in the Championship this season, beating Blackburn 1-0.
It gave the Chairboys a glimmer of hope in their battle to avoid the drop as Blackburn's winless run was extended to five games.
Wycombe were on top in the early stages and came close to taking an early lead as Uche Ikpeazu found space from Curtis Thompson's ball, but his effort was deflected wide by Joe Rankin-Costello.
The hosts were hit by an early injury to Dominic Gape who was taken off on a stretcher.
But they went close again as Admiral Muskwe headed wide right in front of goal from Joe Jacobson's corner.
Blackburn were again without injured top scorer Adam Armstrong with a tendon injury.
They did, however, improve before the break as Rankin-Costello's long-range shot was held at the second attempt by David Stockdale.
Tom Trybull then headed over from Harvey Elliott's corner before Rankin-Costello limped off injured.
Tony Mowbray's side were struggling in the attacking third with Lewis Holtby's mishit effort from Elliott's cross summing up the half.
Wycombe midfielder Anis Mehmeti saw his effort deflect wide after a fine piece of skill just after the break.
From the resulting 47th-minute Jacobson corner, Onyedinma was left unmarked to head past Thomas Kaminski.
It was the fourth goal of the season for the Wycombe forward, who was playing left wing-back, but only his second in the league.
In response Sam Gallagher shot just wide of the post for Blackburn from Joe Rothwell's pass.
Mehmeti continued to cause problems for the Rovers defence and his low shot deflected wide of the post.
Rovers had beaten Wycombe 5-0 in the reverse fixture back in October but were nowhere near as clinical this time around.
Mowbray would have been confident of a push towards promotion at that stage, but their chances are now over and this was a lacklustre display overall which had very much an end-of-season feel.
Mehmeti saw an effort cleared off the line by Barry Douglas, and Taylor Harwood-Bellis was unable to convert a Gallagher corner for Blackburn at the other end.
Mowbray's side went so close to an equaliser two minutes from time as Rothwell's superb run and shot was kept out by Stockdale at point-blank range.
But a rare win will delight Wycombe boss Gareth Ainsworth, a former Blackburn season ticket-holder.
What the managers said...
Wycombe's Gareth Ainsworth: "We changed formation today and it worked. That might have surprised a few people. We've worked on things for two weeks and it paid dividends.
"We soaked up so much pressure and were cramping up at the end, but we were the better side. It's a really good result for us and it gives us a chance. People will be wondering whether we're dead and buried - not a chance! There's never any pressure on us because we're punching so far above our weight, and they beat us 5-0 last time so this feels like a big result."
Blackburn's Tony Mowbray: "We're all disappointed to lose. They scored from a set play, which is their strength and full credit to them for fighting to stay in this league. It's always a difficult game against them because they don't allow you to dominate games. I'm disappointed we could not take the half-chances that came our way.
"We can play pretty good football, but you have to score. We have lost lots of games 1-0 this season when we've had plenty of the ball. We were without our main scorer and Adam can finish it off. It's all about sticking the ball in the net and he can shoot left, right and get it in the back of the net."