Watford's Ben Foster feels sorry for Petr Cech after seeing the Arsenal goalkeeper struggle with playing the ball out from the back.
Foster told BBC's Radio 5 Live that it is hard for a veteran goalkeeper to suddenly change his game, with Cech being asked to take an active part in Arsenal's passing game by coach Unai Emery.
Cech's mistakes with his feet nearly cost his team against Manchester City and Cardiff City, although the 36-year-old has also bailed Arsenal out with a number of key saves.
"Cech is one of the best goalkeepers the Premier League has seen but that really is not his game," Foster said. "His strong points have always been being big and commanding and making saves, but the way football is going now, you almost have to be one of those Ederson type of goalkeepers. It's going to take some time to get used to and I do feel sorry for him."
Emery has decided to stick with Cech even though Bernd Leno, who was signed from Bayer Leverkusen in the summer, is better with his feet.
"He has experience. He is intelligent. He is doing what we want," Emery said. "It's very important for me to continue doing this and to keep improving."
Cech is not the only Arsenal player trying to adapt to Emery's style of play as other defensive mistakes have cost the team as well.
They conceded twice at Cardiff before Alexandre Lacazette scored late to secure a 3-2 win, and have yet to keep a clean sheet in four games.
Lacazette said it is clear the team are still learning the new system, but he is not worried about the problems.
"We learn a lot, but the manager says if we [make mistakes], we can concede a goal," he told reporters. "We just did mistakes because we are learning, like children, so it is OK. It will be better week after week."
Lacazette also said Arsenal's response to conceding two equalisers against Cardiff also showed they are more resilient than last season.
"You can see we had the mentality," he said. "Last season we lost this kind of game. But if you see the faces after the second goal, we had confidence and that was why we came back."