Goals from David Wright and Jason de Vos handed Ipswich victory over Championship leaders West Brom.
The home side did not take the lead until 16 minutes from time when Wright headed in midfielder Liam Trotter's cross from the by-line.
And soon after, Town doubled their advantage when De Vos powered in another header, this time from Gavin Williams' whipped cross.
West Brom went close through Kevin Phillips whose shot struck the bar.
West Brom boss Tony Mowbray:
"We're disappointed with the result, but I'm not going to make any excuses. We were below par.
"Ipswich deserve a lot of credit because they worked extremely hard all over the pitch, especially in midfield, to stop our fluency.
"Their league record at home speaks for itself, so obviously it's a very difficult place to come to."
Ipswich boss Jim Magilton:
"In terms of the second half, that's as well as we've played for some time.
"In the first few minutes we had one or two chances but had a bit of a hangover from our two away games.
"We gave them a bit too much respect. In the second half, though, we were excellent and on the balance of play deserved it."
Ipswich: Alexander, Wright, Bruce, De Vos, Sito, Williams, Garvan, Trotter (Lee 82), Haynes, Walters, Counago (Clarke 88).
Subs Not Used: Supple, Wilnis, Legwinski.
Booked: Williams, Counago.
Goals: Wright 75, De Vos 84.
West Brom: Kiely, Hoefkens, Cesar, Pele, Robinson, Gera, Koren, Greening, Morrison (Filipe Teixeira 78), Phillips (Beattie 66), Miller (Bednar 66).
Subs Not Used: Albrechtsen, Brunt.
Booked: Hoefkens, Cesar.
Ref: Trevor Kettle (Rutland).