Northern Ireland’s Spain ‘82 World Cup hero Gerry Armstrong says the £80million Real Madrid have spent bringing Cristiano Ronaldo from Manchester United will be a waste if they don’t strengthen up at the back.

“£80million is a ridiculous amount of money to spend on one player,” he said.

“But to be honest, it wasn’t a surprise to me and I’ve known for six or seven weeks that the deal would go through.

“But for me Real’s best player last season was their goalkeeper and that tells you a lot about their defence.

“They need to sign a left back and one, maybe two centre halves.

“Those sorts of signings don’t generate the same sort of headlines as Ronaldo, but they would be just as important.”

Northern Ireland hero Armstrong, now a commentator on La Liga for Sky television, says Ronaldo will enjoy football in Spain more than in the Premier League.

“The style of play will suit him more and it won’t be so physical,” he said.

“Playing with players like Kaka can only help him as well and I believe that they will sign David Villa as well in the next couple of days.

“They have £300m to spend on bringing new players to Madrid but like I say, they need to strengthen their defence.

“Barcelona aren’t the greatest at the back either, but for me, they will still be favourites to take the title next year.”