Sam Allardyce saw his Blackburn Rovers side surely secure their top-flight status with this victory at Ewood Park.

He has always believed 40 points would be enough to stay up and they achieved that mark by overcoming Portsmouth.

Goals from Morten Gamst Pedersen and Benni McCarthy (penalty) in each half saw Blackburn maintain their good home record.

They have lost only one of 10 Barclays Premier League matches on their own patch since Allardyce arrived as manager in December.

He has steadied the ship after a dreadful start and steered his side away from trouble.

With the rain teeming down and conditions difficult, Portsmouth goalkeeper David James took no chances in the 11th minute, punching clear an inswinging corner from El Hadji-Diouf.

Blackburn were having the majority of possession and carved out a good chance in the 29th minute when a clever backheel from McCarthy released Stephen Warnock. He played the ball across the face of the area but Diouf was unable to take advantage.

However Blackburn made the breakthrough a minute later following a moment of indecision from James.

He was beaten to the ball by Christopher Samba following a cross from Stephen Warnock and it broke to Pedersen, who forced it home.

It was the Norwegian's first goal of the season and put Blackburn in the driving seat.

James, meanwhile, was left to reflect on failing to clear his lines when he had the chance.

Portsmouth, however, came close to equalising in the 43rd minute when Hermann Hreidarsson got on the end of a free-kick from Sean Davis only to head narrowly wide of the post.

Blackburn hit back and almost extended their lead two minutes into the second half following a long throw from Pedersen.

Samba flicked the ball on and Warnock rifled in a volley, only to see Kaboul get a vital touch.

Blackburn kept up the pressure and Pedersen whipped in a 35-yard free-kick that James tipped over the bar.

Samba, who was making a nuisance of himself, then found the net but his effort was ruled out for an infringement.

Blackburn, however, extended their lead in the 58th minute when Hreidarsson handled as McCarthy clipped the ball into his path.

McCarthy sent the penalty into the corner to take his tally for the season to 13 goals with his third in five matches.

The South African has risen to the challenge in the absence of Roque Santa Cruz and Jason Roberts through injury.

It was no more than Blackburn deserved and Portsmouth again found themselves on the back foot in the 63rd minute but Samba headed wide following a cross from Pedersen.

Portsmouth suddenly stepped up the pace and sub Jermaine Pennant clipped a shot wide of the post in the 71st minute after being released by Peter Crouch.

Five minutes later they pressed forward again and Nelsen did well to scoop away sub John Utaka's effort.

The captain could not conceal his anger at some sloppy play by his side, which allowed Utaka the opening.

Utaka then squandered a glorious chance of pulling a goal back in the 87th minute when he sent his penalty high over the bar.

The spot-kick was awarded after Andrews was adjudged to have handled the ball when Kanu played it in.