The Italian boss says the ex-Chelsea 'keeper has boosted the confidence of the Gunners.
Sevilla host Manchester City in the Premier League on 3 November. Find out where to watch the game live in the UK.
But Kevin Gameiro is out after suffered an injury during the La Liga defeat against Villarreal.
The former Arsenal star has signed a three-and-a-half-year deal until the end of the 2018-19 season.
Arsenal have now won five straight Premier League games and are level on points with Manchester City at the top of the table.
United have lost ground on the PL pacesetters Manchester City and Arsenal after the draw against Palace.
Manchester City host Norwich City at the Etihad Stadium. Find out where to follow the game in the UK.
Manchester City beat Norwich 7-0 on their last visit to the Etihad Stadium.
United have been knocked by lower league opposition in the League Cup for a second consecutive year.
IBTimes UK provides live coverage of the fifth round draw in the League Cup.
Manchester City host Crystal Palace in the Capital One Cup on 28 October. Find out where to follow in the UK.
The holding midfielder had rejected a previous offer from the current Europa League champions.
Josep Maria Bartomeu expects Argentina captain to retire at Nou Camp.
Ecuador international played through the pain after suffering first-half knock.
City return to the top of the table with dour draw as Harry Kane hits a hat-trick at Dean Court.
Louis van Gaal believes players keen to join Manchester United.
Manchester United's Anthony Martial named Premier League Player of the Month for September.
The Argentina captain is more open to the idea of a transfer to England, according to Guillem Balague.
Manchester United face Manchester City in the Premier League clash on Sunday. Find out how to follow the match live in the UK.
Anthony Martial has scored five goals in all competitions for Manchester United.
Captain has missed City's last two games.
Louis van Gaal wants the Premier League to introduce a winter break to rest players.