United manager Alex Ferguson has only lost two of 25 matches against teams managed by his former players at Old Trafford and there was little sympathy shown to under-pressure Paul Ince on Wednesday when his Blackburn Rovers side were beaten 5-3 in the League Cup quarter-final.
Ferguson also got the better of Mark Hughes, his former striker and boss of Manchester City, in a 1-0 derby triumph last weekend that put United hot on the heels of Premier League leaders Liverpool.
Last week's 4-1 home defeat by Bolton Wanderers increased the pressure on him but it was still a surprise that Keane decided to leave the Stadium of Light after the first major slump in his managerial career.
United are under pressure of a different kind as they seek to build on last weekend's win at City.
"You'd love to be leading the league from day one, but it doesn't often happen like that. We're all still confident and believe we can go on a 10 or 20-game unbeaten run," Ferdinand said on Tuesday.
"Our aim now is to make sure we're within touching distance at Christmas so we can kick on next year and reel those teams in," he told reporters.
Wigan will not relish playing Arsenal's first team after losing to the reserves and juniors 3-0 in an earlier round of the League Cup at the Emirates three week ago.
