Former Blues boss Tony Pulis brings his Stoke side to the south coast for Saturday's tea-time kick-off.
And Utaka believes that Pompey must beat the Potters - and aim to take maximum points from all their remaining seven home matches.
He told the club's website: "We have to stay optimistic and try to win all of our games at Fratton Park.
"In fact we will go into every match thinking that we can win and get the points we need. You have to respect your opponents. Stoke are a good side - there's no doubt about that. But we need the points, so we have to do everything we can to win the game.
"It was great to win against Southampton. Any win gives you a lift and can help you to win the next game. The result was beautiful and was just what the fans deserved.
"It was a great atmosphere - games like that are what football is all about. But now we need to build on that - starting with Stoke on Saturday."