Manuel Almunia believes Arsenal have the mental strength to stay in the title race until the very end.
The Gunners moved to the top of the table on Saturday with a hard-fought 2-0 victory over West Ham at Emirates Stadium.
Thomas Vermaelen was sent off for bringing down Guillermo Franco in the box on the stroke of half-time but Almunia brilliantly saved Alessandro Diamanti's penalty.
Manchester United replaced Arsenal as leaders by beating Liverpool the next day and will be in control of their own destiny as long as they keep winning.
But Almunia has warned that Arsenal are ready for the challenge and will look to capitalise on any slip-ups.
"This team is full of confidence, character, spirit and fight," the goalkeeper told Arsenal TV Online.
"It was crucial to win and shows that Arsenal are at the top of the table to fight for the league.
"We will continue to put pressure on them until the end of the season, right up until we have the last possibility to win the league - that is all we can do."
Arsene Wenger has been delighted with the way that Almunia has played since the turn of the year and paid special tribute to his performance against West Ham.
"In the last two months, Almunia has been outstanding, and has come back to his top form. You have to give him credit," said the manager.
"He kept us in the game on Saturday, and when every player starts to be decisive at some moment in the game, that is a good sign."