West Ham United became the second Premier League team to be eliminated by lower-league opposition in this season's FA Cup when they crashed 5-0 at Nottingham Forest on Sunday.
Jamie Paterson was the star man for Championship side Forest with a 14-minute hat-trick against a second-string West Ham team featuring three young debutantes.
West Ham's defeat at the City Ground follows Aston Villa's 2-1 loss at home to third-tier Sheffield United on Saturday.
Forest took a 12th-minute lead with an audacious dinked penalty from Algerian midfielder Djamel Abdoun, after Paterson drew a foul from George Moncur with a sharp Cruyff turn.
In response, Ravel Morrison saw a free-kick palmed over the crossbar by Karl Darlow, but Forest finished the first half strongly.
West Ham goalkeeper Adrian had to save with his feet from Eric Lichaj and Henri Lansbury blazed the rebound over the bar.
Paterson added a second in the 65th minute, drilling home a low shot, and he made it 3-0 six minutes later by stabbing home from Lansbury's square pass.
The 22-year-old forward completed his triple in fine style in the 79th minute, drifting past three visiting defenders on the edge of the penalty area before lashing a low shot into the bottom-left corner.
Andy Reid slammed home in injury time to complete a miserable afternoon for Sam Allardyce's West Ham, who are currently second from bottom in the Premier League table.