When Arsenal signed Petr Čech in the summer, many people seemed unsure of the impact it would have.

Of course Čech is a top goalkeeper, one of the best, but was he still at that level? He had barely played in a year and was already 33 – was he worth the huge transfer fee and contract Arsenal would have to pay?

We’re halfway through his first season in north London and Čech has been worth every penny and more. But surprisingly, even Arsène Wenger had his doubt.

“[When he signed] I didn’t know what kind of shape he was in physically because he hadn’t played,” the Arsenal manager has admitted to the club website“When I met him I was quickly reassured of his desire to do well and his motivation. I didn’t know how much he could still produce physically.

“He hadn’t played and was battling a drop in physical aptitude but I knew the potential was exceptional having played against him for 11 years in the Premier League. It was a question of physically, can he still do it?”

He most certainly can. The goalkeeper produced another man of the match display last week to keep Stoke at bay and clinch another crucial point for Arsenal.

Sunday sees Čech come up against Chelsea, a club he spent over a decade with. Another top performance would be huge for Arsenal’s title chances. His form has seen David Ospina pushed to the outskirts of the squad, but Wenger can’t have any regrets.

“It was a very, very difficult decision for me because I rate Ospina highly. He is a keeper who is underrated, especially in England. But signing Cech was maybe one of the few opportunities to say, ‘Okay, this is an obvious transfer’. It was more to say, ‘If I don’t do this, it would be a mistake’.”

It would have been, but it’s one we avoided.