Everton 0 Blackburn 1
Jonathan Stead's goals last season saved Blackburn from relegation and his first of this campaign could well have the same end product.
The England under-21 striker arrived last term from Huddersfield and hit six goals in 13 tension-packed matches to keep Blackburn in the top flight.
He has not been as prolific this season, but the one he struck to secure victory at Goodison Park midway through the second half could be equally priceless come the end of the season.
The result gives Liverpool a lifeline in the race for the fourth Champions League spot - with the two teams shaping up in their next Premiership match at Anfield.
FA Cup quarter-finalists Blackburn had two early opportunities when Morten Gamst Pedersen's long throw was flicked on by Steven Reid and kicked away from the goalmouth by Alessandro Pistone.
Then Nils-Eric Johansson sent another header into the danger area and Paul Dickov flung himself at the ball, got a connection, but was flattened by Nigel Martyn for his troubles.
Everton should have been ahead when Martyn's long kick was flicked on to Marcus Bent but he was thwarted by Brad Friedel 10 yards out.
Everton increased their tempo in the second period, but it was Blackburn who could have taken the lead when Thompson stabbed inches wide from a Reid flick-on.
Ferguson went close when he rose high to head over from a Leon Osman cross and then when he nodded an Alessandro Pistone cross wide.
Rovers made the decisive breakthrough in 71st minute when Joseph Yobo's headed clearance was knocked back by Mokoena to Reid, who fed Stead.
The striker moved forward a couple of yards before lashing a drive from just inside the box which went across Martyn and just inside his far post.
Everton mounted a last-ditch charge and Osman hooked just wide after Rovers failed to clear yet another free-kick.
Friedel then blocked another Osman effort with two minutes to go but Everton fell away and slumped to their fifth home defeat of the season, one which could be the most costly.