Jason Roberts made a point to Sam Allardyce, at the same time helping Blackburn to three as they shrugged off their first-half languor to record a victory over Portsmouth that was ultimately as emphatic as it had seemed unlikely at half-time.
Roberts, who has been marginalised in the Ewood Park attacking stakes by the form of Franco Di Santo, was sent on by the Blackburn manager along with Benni McCarthy after Portsmouth went in at the break looking good value for Jamie O'Hara's early goal.
The former Wigan player, who also lost ground when he contracted swine flu, swiftly brought Blackburn level. Ryan Nelsen put them ahead, and Roberts pounced again in the closing minutes to turn the jeers at the interval into cheers at the end.
Asked about the double substitution, Allardyce replied: "I think I might just have earned my money this week. I don't normally get so radical, but it was our worst first half this season, without one attempt on goal."
Allardyce "understood" the booing. "We were poor in the first half. But it's the third time running here that we've come from behind to win, after the Aston Villa and Burnley games, and the quality of our free-kicks and corners was decisive."
Paul Hart also identified the set-pieces as decisive, lamenting Ports-mouth's defending of them in the second half. "It was sacrilege," the Pompey manager said. "If you don't defend those against Blackburn, you're going to be in trouble."
Portsmouth, who knew they could escape the bottom three and dump Blackburn in 20th place by winning, deserved their 15th-minute goal. Aruna Dindane's pass found the on-loan Tottenham midfielder O'Hara with space and time to fire past his former White Hart Lane team-mate Paul Robinson from 30 yards. Blackburn's problems would have worsened if referee Andre Marriner had brandished the red card to Pascal Chimbonda after O'Hara's dogged pursuit of another old Spurs colleague provoked the defender into lashing out 10 minutes before half-time.
Enter Roberts, who was soon stabbing the ball past David James at point-blank range after Nelsen had headed David Dunn's corner to his feet. Another flag-kick by Dunn, another goal, and again it was Nelsen's head that met the ball, though this time it was no mere assist.
Portsmouth's fluidity had long since turned to scrappiness before Roberts, sidefooting in McCarthy's near-post cross for the third goal of his stop-start season, applied the icing.
Referee: Andre Marriner
Man of the match: Roberts