Arsenal manager Arsene Wenger has hailed the improved form of Wojciech Szczesny following the goalkeeper's 100th Premier League appearance for the club.
The Poland international, 23, reached the landmark on Saturday as the Gunners earned a 2-0 win over Fulham to stay at the top of the table.
"Certainly a part of his improvement is mental because he's more mature," he told the club's official website.
"His decision-making is cleaner, sharper, quicker. He was always a very talented boy but because he's intelligent he learns quickly from experience.
"I'm happy that I always gave him the confidence because he's developing very well into a very strong goalkeeper and today certainly nobody would question that he's one of the top five goalkeepers in the Premier League."
Arsenal return to action on Friday night when they host Coventry City in the fourth round of the FA Cup.