"As a player he's a nightmare to play against, horrible. It's funny because I've had a few run-ins with him on the pitch and I think I'll be reminding him of that," said the Liverpool skipper.
"But, believe me, I'll be glad to have a player like that on my side. We need characters like that on our team.
"To win the league and other trophies, you need to have characters who have also got the quality - and Craig has definitely got that.
"As a player, you can be too nice. All the best players are top quality but they also have the character to go with it, that's what I like in a player, and what I like about Craig.
"Maybe we have been a bit nice as a team in recent seasons but we are toughening up, and we are becoming a very difficult side to play against. That's what we need if we are going to win the title."