The Tigers invested £13.5million in the two strikers last month and have reaped an early dividend with both scoring in a 2-0 win at the Stadium of Light.
Steve Bruce: "All credit to the people who employ me to have the vision to go and do it.
"It's paid its reward today. Longy has got two in two and it's the way they play and the way they are as a pair.
"They work hard for the cause and they are a good pair of strikers. I wouldn't want to play against them because they caused all sorts of problems today.
"If you look at all the bottom half of the division, we all can't afford a (Sergio) Aguero or an (Alvaro) Negredo or a (Luis) Suarez, and that's the hardest part.
"I have always said, even in my Sunderland days here, you are only as good as your strikers, and I have still got that belief now.
"For all the wonderful possession we had, we still needed to stick the ball in the back of the net and they have done it today."