Barton reckons former Newcastle teammate Carroll will be desperate to make an impact when the new season begins in August after injuries stalled his Liverpool career following a January move from St James' Park.
"It's always difficult when you go to a new football club and you're not fully fit," Barton told liverpoolfc.tv. "He had a niggling injury when they signed him. He'll be looking to get pre-season under his belt and look to kick on and show Liverpool what an asset they've acquired.
"He's a great lad and we were all gutted to see him leave Newcastle but it was a no-brainer, really. He had to go and test himself at a fantastic football club with great tradition. I stay in touch and we're all wishing him well but not when he plays against us.
"I haven't been watching Liverpool with a lot of interest but they had a great run towards the end of the season. We played them at Anfield and they were magnificent on that day.
"We thought we'd have a chance looking at side they had and the individuals but it was a great team performance - certainly a better team performance than we saw in December at St James' Park."