Francois Zoko and Yoann Arquin netted for Notts County to earn a 2-0 win and send 10-man Portsmouth crashing out of the FA Cup at Fratton Park.
The 2008 winners ended the game with 10 men after loan signing Scott Allan was sent off after 75 minutes, which cued a touchline melee that saw Pompey's first team coach Ashley Westwood sent to the stands.
Notts County should have led after 18 minutes when Jamal Campbell-Rice danced his way down the right. He squared it to Arquin, who miscued his shot on to the crossbar.
But the Magpies stole ahead in first-half stoppage time when Zoko nodded home Alan Judge's looping cross from the right.
County doubled their lead after 56 minutes when Campbell-Rice hung up a beautiful cross from the left, which Arquin netted with a textbook header.
Pompey's plight worsened after 75 minutes, when Allan was given a straight red card for kicking Campbell-Rice - just three minutes after being cautioned for felling the County winger.