West Ham became the second Premier League team to be eliminated by lower-league opposition in this season’s competition when they were crushed 5-0 by Championship side Nottingham Forest at the City Ground.
A day after Aston Villa fell to third-tier Sheffield United, West Ham were undone by a 14-minute hat-trick from Forest forward Jamie Paterson, sandwiched by an early Djamel Abdoun penalty and a late Andy Reid strike.
West Ham manager Sam Allardyce made nine changes to his starting XI and gave debuts to three young players, but he told ITV: “What choice did I have? I don’t think I had one.”
“I make the decisions for the benefit of everyone at the football club. We have a huge amount of problems in terms of available players,” he added.
Sunderland overcame third-tier Carlisle United 2-1 at the Stadium of Light to take their place in the fourth round.
Adam Johnson put Sunderland ahead with a fine 34th-minute free-kick and then supplied the cross from which Sean O’Hanlon put through his own goal after Matty Robson had leveled the scores.
A 90th-minute strike from 20-year-old French midfielder El-Hadji Ba completed victory for Gus Poyet’s men.
In Sunday’s other tie, Port Vale were taken to a replay after they were held 2-2 by Plymouth Argyle.
Additional reporting by staff writer