The pair both started out at Middlesbrough's academy before going on to play for the first team and have now been reunited at the Stadium of Light after Black Cats boss
Sunderland captain Cattermole hailed Johnson's skill and believes he will make a huge impact back in his native north east. "Johnno is a great talent, always has been," Cattermole said.
"He has that ability to go past players and our fans will really like him.
"I'm sure he'll do great with us and I think he'll find a lot more space and grass in front of him than he was used to at Man City.
"Adam will love the challenge of playing here and is from the area too. I spoke to him (about the move) and told him he will love it at Sunderland.
"He's a great lad too and will fit in no problem. I'm sure we'll see that in his performances.
"It's funny - everyone seems to go their own way in football and move round clubs, so it's great to be playing alongside him again."
Johnson signed for Sunderland on Friday just hours after Wolverhampton attacker
Cattermole believes Fletcher will be able to provide some much-needed firepower alongside
"Steven scored goals for a struggling team last year and hopefully we can create even more chances for him," Cattermole said.
"I'm sure Steven will start banging in the goals here and it's nice to see him join.
"He probably wanted to get it done a bit quicker but it got there in the end.
"It's important to remember the other signings too - both
Professional Footballers' Association chief executive Gordon Taylor has confirmed the union has been contacted by Sunderland players about manager Paolo Di Canio and that it is investigating the recent fines issued by the Italian.