Chelsea skipper John Terry has hailed the form of fellow centre-half Alex and admits he has given Carlo Ancelotti a selection headache.
The Brazilian has often been resigned to back-up duties at Stamford Bridge, with Terry and Ricardo Carvalho regarded as the Blues' first-choice pairing at the heart of their defence.
He has, however, proved to be an able deputy when called upon and has rarely let the side down.
The burly defender put in a man of the match showing in Chelsea's comfortable 2-0 victory over Stoke in the FA Cup quarter-finals on Sunday, and Terry is among those keen to pile praise on the Samba star.
"He amazes me how he comes in and plays so well," said the England international.
"He is not first choice regularly but when he does come in he is brilliant. He made two great tackles in the game (against Stoke), especially the one against Tuncay."
Terry admits Alex is pushing hard for a regular role in Ancelotti's plans and accepts that he and Carvalho, who is currently struggling with a knock, must raise their game if they are to keep him on the sidelines.
"It is down to myself and Riccy to maintain our place in the team," he added.
"Riccy is out with a slight hamstring strain but hopefully he will be back soon and when players come in and play as well as Alex, it gives the manager a problem which is good for the squad."