Chelsea defender Alex believes Arsenal are likely to be the club's strongest challengers for the Premier League title this season.
Arsenal had looked to be all but out of contention for the league after the 3-0 defeat at home to Chelsea at the end of November, but they have since recovered their form while both Chelsea and Manchester United have dropped points.
Arsenal are currently two points behind United and four behind Chelsea with one game in hand and, while they still have much to prove, Alex believes they are the biggest threat to Chelsea's hopes of regaining the trophy.
"Arsenal will give us the best challenge this season," he said in the London Evening Standard. "They play well, they are playing better and always have confidence in all the games. They are at their best this season."
Alex has struggled for first-team football this season and a number of clubs are said to be monitoring his situation, but he feels confident Carlo Ancelotti will give him the chance to fight for his place and wants to remain at Stamford Bridge.
"The coach has the confidence of all the players," he said. "We have a group capable of winning the Champions League and Premier League.
"It's been difficult for me because we have a good defence, but I am very happy to battle for my place, get chances to play and stay in the group.
"I am very happy to stay here, to play for Chelsea and to play more and more games. We have been playing our best football this season since I came to the club."