Manchester City forward Robinho has backed the club's pursuit of Chelsea captain John Terry.
Having landed Gareth Barry, Roque Santa Cruz, Carlos Tevez and Emmanuel Adebayor already this summer, City boss Mark Hughes is keen to bolster his defence.
England international Terry is a long-term target but Chelsea have made it clear that they have no intention of letting the centre-back leave.
Brazilian star Robinho, who joined City from Real Madrid for £32.5million, recognises the need for defensive reinforcements and feels Terry could make the club 'unbeatable'.
He said in the Sunday Mirror: "There is no longer a top four.
"We have made it a top five. From this season we have to go in with the mindset we're one of the very best clubs.
"I'm delighted we've signed Tevez. He is a world-class player and it would be fantastic for me to play alongside him.
"It was a shame the Samuel Eto'o deal couldn't happen for whatever reason, because he is another world-class player and the sort this club is looking to sign at the moment. But we have already signed Santa Cruz and now there is the possibility of Adebayor as well.
"While I've always urged the club to sign players like Tevez and Kaka when there has been a chance, I also know you have to build from the back.
"You can have the best attacking six players in the world, but unless the defence compliments it then you will not win anything.
"I don't know anything about the John Terry deal apart from what I have read, but he is the sort of world-class leader we need at the back.
"I have said before when you build a house you start from the bottom.
"If John does not happen then there are plenty of quality defenders in Europe.
"If the players we have signed and the players we may sign all work well together then on our day we can become unbeatable - and not just in England, but in Europe as well."
He added: "We will be looking to win all the competitions we are in and that means having a squad of world class players.
"All the top clubs have players competing for places, and we now have to look at ourselves as a top club.
"People will need to start taking us very seriously."