A day after United's surprising 4-0 loss at MK Dons, another third-tier club, Leyton Orient, won 1-0 at Aston Villa, and fourth-tier side Burton edged past QPR by the same score.
But two topflight sides eased through with 3-0 wins, with Stoke eliminating Portsmouth and Sunderland ousting Birmingham. Stoke and Sunderland were then drawn to play each other in the third round when the teams playing in Europe enter the competition.
Several Premier League sides will be facing lower-ranking opponents, with Chelsea drawn against Bolton, Liverpool against Middlesbrough, holder Manchester City against Sheffield Wednesday, and Tottenham against Nottingham Forest. In all-Premier League encounters, Arsenal hosts Southampton, Everton travels to Swansea, West Bromwich Albion plays Hull, and Crystal Palace takes on Newcastle.