The British & Irish Lions and Wales star quit the Arms Park for Racing Metro in the summer.
And Hewitt, who has spent much of his career playing second fiddle to Roberts, insists he can fill the void and make the number 12 jersey his own.
“I suppose it’s always been in the back of my mind trying to get in the side ahead of Jamie,” said Hewitt.
“He’s a quality player and he brings that experience and it’s always been tough. I hope now to be able to step up to the plate.
“There are a number of good boys in the centre position – Gavin Evans, Owen Williams, Cory Allen, Richard Smith and
Tom Pascoe – and it’s going to be a good dogfight this year to see who gets the 12 and 13 jerseys.
“But I’m 28 now, so it’s about time I cemented that position. With Jamie gone, it does open up opportunities and I plan to take those with both hands when they come.”
Hewitt will take centre stage tomorrow as the Blues play their first competitive fixture on the newly installed 4G artificial pitch at the Arms Park.
And the Blues will be aiming to return to winning ways following their 22-15 opening defeat to Glasgow Warriors in the RaboDirect Pro12.
“It was a bit of a consolation getting a losing bonus point, but we would have much preferred the win,” said Hewitt.
“We were ahead with about 15 minutes to go and then ill discipline threw it away.
“But it was a good gutsy performance by the boys and a point is consolation.
“I don’t think many teams will go up there and do that this season.”
And the Llantwit Major product has urged his teammates to keep their discipline against the Irish province after seeing two players – Owen Williams and Macauley Cook – sin-binned at the Scotstoun Stadium.
“Discipline has been a massive message this week,” added Hewitt.
“It’s been really drilled into us.
“Connacht have got our old team-mate Dan Parks at fly-half and he will kick the penalties from anywhere if we concede them, so it’s of the utmost importance to keep our heads about us.
“They are a bit of a fighting side and we never have an easy game against them. We expect them to bring a strong side, but we will be aiming to better them.”
