Benni McCarthy had been plotting an escape route from Ewood Park before Sam Allardyce replaced Paul Ince as manager of Blackburn Rovers seven weeks ago, but the South Africa forward continued his resurgence with his sixth goal under Allardyce to guide his team into the FA Cup fifth round.

McCarthy’s close-range header, two minutes from the end of extra time, finally settled an uneventful fourth-round replay and secured Blackburn a home tie against Coventry City on February 14.

McCarthy’s reversal of fortune has been mirrored by Blackburn’s improvement under Allardyce, who has yet to taste defeat in his new job, although he admitted fearing that his unbeaten run would end last night.

“After Sunderland scored, there were times when I wondered whether we would score one goal, never mind two,” Allardyce said. “Their goalkeeper made some unbelievable saves and we missed some sitters, but Aaron Mokoena’s goal and Benni’s winner settled the tie when I was beginning to wonder if we were going to clinch it.”

In a lively start, Zurab Khizanishvili hit the post with a header for Blackburn before David Healy opened the scoring in Sunderland’s first attack after seven minutes.

Mokoena equalised eight minutes before half-time with a 30-yard strike that beat Craig Gordon, the Sunderland goalkeeper, after taking a deflection off Anton Ferdinand. It was only the South Africa midfield player’s second goal in four years at the club.

From that point on, the game deteriorated rapidly and it was only enlivened by a series of impressive saves by Gordon, who was making his first appearance since suffering a broken ankle in training ten weeks ago.

Gordon denied Carlos Villanueva and Jason Roberts and his heroics looked destined to take the game to a penalty shoot-out, but Sunderland’s failure to mark McCarthy inside the six-yard box proved decisive as the former Porto forward headed Villanueva’s cross past Gordon to give Blackburn a deserved victory.

Blackburn Rovers (4-4-2): P Robinson — D Simpson, Z Khizanishvili, R Nelsen (sub: A Ooijer, 87min), G Givet — C Villanueva, A Mokoena, D Dunn (sub: Tugay Kerimoglu, 61), K Treacy — J Roberts, R Santa Cruz (sub: B McCarthy, 72). Substitutes not used: M Bunn, M G Pedersen, M Olsson, A Doran. Booked: Simpson, Treacy, Mokoena.

Sunderland (4-4-2): C Gordon — M Kay (sub: P Bardsley, 56), A Ferdinand, D Collins, G McCartney (sub: , N Luscombe, 106) — S Malbranque (sub: D Yorke, 76), G Leadbitter, A Reid, C Edwards — D Healy, D Murphy. Substitutes not used: N Colgan, D Whitehead, K Richardson, J Colback. Booked: Kay, Leadbitter.

Referee: P Dowd.