SAM Allardyce believes Jason Roberts should be Blackburn Rovers’ “ugly bulldog” after his second half cameo inspired his side to a 3-1 win over Portsmouth.

The powerful striker was introduced at half time, along with Benni McCarthy on Saturday, with Rovers trailing 1-0 but Roberts’ second half double helped turn their fortunes around.

Roberts has had limited first team opportunities over the past two months, due to a combination of loss of form and swine flu, but tormented the visitors’ frail defence with his physical presence.

Allardyce said: “I think it is great for his confidence.

"Nothing gets a player on form than to score two goals like he has scored today.

“He looked extremely strong and robust, which is what we want to see.

"He should be the ugly bulldog for me. He won't like me saying that but he should be.

“He should be snarling and biting and snapping at centre halves all day.

"I think that is his major strength. And when he is like that he becomes unstoppable.

And today we had quality finishing.

“He has helped us turn the game in our favour. It has given Franco a bit more support and we have got Benni on with the quality he has got - which sometimes we do miss.”