Championship big guns Aston Villa suffered a surprise second-round defeat, which will come as a blow to manager Steve Bruce.
Villa came a cropper 1-0 at League One Burton Albion, for whom Liam Boyce took a pass from Scott Fraser seven minutes into the second half and lashed home.
But there was drama in the 89th minute when Burton's Kyle McFadzean handled in the area and was sent off.
Up stepped Albert Adomah but his spot-kick was saved by Harry Campbell, who had replaced injured Stephen Bywater in the Burton goal after 31 minutes.
Frank Lampard's Derby won 4-0 at Hull City with a dominant display.
Martin Waghorn put them ahead on 24 minutes with a stylish finish and Florian Jozefzoon burst forward to find the corner and make it 2-0 six minutes before the interval.
Brandon Fleming put the ball into his own net late on and Chelsea loanee Mason Mount added a stylish fourth.