Arsenal forward Theo Walcott says the arrival of goalkeeper Petr Cech in the off-season has completely changed the club's back four.
Cech, who arrived from Arsenal's London rivals Chelsea, kept his seventh clean sheet of the league season in the club's 2-0 win against Aston Villa on Sunday.
The 33-year-old has kept the equal most clean sheets this season, with Arsenal also boasting the second best defensive record in the Premier League.
Walcott hailed the Czech Republic international's impact on the team as Arsenal continue to establish themselves as challengers for this season's title.
"He's changed us completely in that back four. He's a talker, he believes in us all," Walcott told Arsenal Player.
"That's why he wanted to join us and having that presence behind you is always nice. He's very commanding, he's a leader in the dressing room as well.
"From when we signed him, we all knew how good he was [after] what he achieved at Chelsea."
Arsenal's next test is at home against third-placed Manchester City on December 21.
