Barcelona midfielder Sergio Busquets believes that Atletico Madrid have become the "complete team" under Diego Simeone.
La Liga leaders Barca host second-placed Atleti on Sunday and the Spain international feels that the Madrid outfit are now a major force under their Argentine coach.
"With Simeone in charge, they have become a complete team that makes you work hard for a win," said Busquets.
"Atletico finished very well last season and have continued that form this term. They have become a rival this season because with nearly half the season gone, they are near the top of the table."
Simeone took over at Vicente Calderon in December 2011.