Onuoha said: "He always seems very calm in any situation and that's what makes him such an important part of any team.
"He's a very good defender, too, which makes him an extremely valuable player for both club and country.
"Having played against him, I know he's very strong and commanding.
"But it's not just that. He makes things look so easy. England's two first-choice centre-backs, Rio and John Terry, are the benchmark for all players.
"They are not just good defenders - they can play football.
"We all know that if we want to get near them then we have to keep improving. We have to keep believing."