Manchester United manager Sir Alex Ferguson believes a refocused Barcelona pose the biggest threat to his team's hopes of retaining their Champions League crown.
English sides have once again dominated the world's premier club competition this season, with United one of four teams from the Barclays Premier League to reach the quarter-finals - along with Liverpool, Arsenal and Chelsea.
It is the Red Devils' bitter rivals, Liverpool, who have been pinpointed as the team in form following their 5-0 aggregate mauling of Spanish giants Real Madrid in the last 16, but Ferguson insists it is Barcelona - who United cannot meet until May's final - who are the real class of the field, he said: "Barcelona are the form team, they have been terrific this season and everyone is taking notice of them."
He added: "Their first-half performance against Lyon in the second leg of the first knock-out round (which they won 5-2 at the Nou Camp) was absolutely brilliant - they were four up in no time.
"They can be a threat to anybody and are quite rightly one of the favourites. The English teams have proven the strength of the Premier League in recent years.
"Last season we had three in the semi-finals and two in the final, the previous year there were three in the semis and Liverpool made it to the final.
"But we have to recognise that our threats don't just come from England, the big one will come from Barcelona."
The Catalans won the Champions League in 2006 under the guidance of Dutch coach Frank Rijkaard, who developed a side renowned for their offensive brilliance.
A recent, brilliant 6-0 mauling of Malaga in La Liga showed that facet of their play remains intact, but Ferguson believes it is the new-found defensive solidity engendered by current boss Pep Guardiola which has taken them to a new level.
"I'm not sure they have improved a lot from when we played them last season but they have had a better defensive record since Guardiola took over as coach last year," Ferguson told Inside United.
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