Petr Cech
Petr Cech has secured seven Premier League clean sheets for Arsenal since his summer move from ChelseaGetty

Theo Walcott has said the summer signing of Petr Cech has been the key difference for Arsenal this term, with the former Chelsea keeper being behind a complete change of the back four's attitude. The England international also paid tribute to Olivier Giroud, following the French striker's dream week that saw him hit a hat-trick past Olympiacos in the Champions League and score against Aston Villa at the weekend.

Cech called time on his successful career at Stamford Bridge last summer after being usurped as the club's number one by Thibaut Courtois. Arsene Wenger took advantage of the situation by luring the 33-year-old to North London in a deal with around £10m ($15m).

Despite a rough home debut against West Ham United, Cech has since returned to his top form. He has secured seven clean sheets so far in the league, with his shutout against Villa taking his total to 169 – equalling David James' Premier League record.

"From when we signed him, we all knew how good he was [after] what he achieved at Chelsea," Walcott told Arsenal Player. "On a personal level, for him it's great.

"He's changed us completely in that back four. He's a talker, he believes in us all. That's why he wanted to join us and having with that presence behind you is always nice to have. He's very commanding, he's a leader in the dressing room as well, he always likes to talk."

Giroud, meanwhile, opened the scoring in the win over Villa with his 14th goal of the campaign, helping the Gunners to move to the top of the Premier League. Walcott has hailed the Frenchman's contribution to the side, calling him a "dream to play with" due to the way he makes life easier for his teammates.

"It's not just his goals, it's his general play and everything about him," Walcott said. "The way he holds the ball up, he blocks it and defends it, and he works hard from the team from defensive corners and everything.

"He's in great form at the moment. He's a dream to play with and he makes our job a lot easier. As soon as I won the penalty, I just knew that he would score. Confidence is streaming through him and you want that in the busy Christmas period. You want players that are on form and he's definitely one of them."