Extra-time goals from Dave Kitson and Leroy Lita saw Reading through to the second round against 10-man Swansea.
Kitson's clinical finishing proved Swansea's undoing
Kitson opened the scoring with a superb lob over Willie Gueret, but 10 minutes from time Adebayo Akinfenwa's header off Ijah Anderson's cross levelled it.
Anderson was dismissed for a second bookable offence in the 85th minute.
The Swans wilted in extra time, Kitson drawing Gueret to finish clinically before James Harper's cross set up Lita for a superb left-footed finish.
Swansea manager Kenny Jackett, livid at the six yellow cards and one red dished out by referee Keith Stroud, was ordered from the touch-line in the closing moments.
Reading: Stack, Makin, Sonko, Ingimarsson, Shorey, Hunt, Harper, Sidwell, Oster (Little 14), Kitson, Doyle (Gunnarsson 71), Little (Lita 82).
Subs Not Used: Hahnemann, Convey.
Booked: Harper, Kitson, Gunnarsson.
Goals: Kitson 14, 95, Lita 114.
Swansea: Gueret, Tate, Edwards, Austin (Anderson 45), Ricketts, Britton, Martinez, Tudur-Jones (MacDonald 101), McLeod, Akinfenwa, Connor.
Subs Not Used: Murphy, Thorpe, Goodfellow.
Sent Off: Anderson (85).
Booked: Tudur-Jones, Martinez, Anderson.
Goals: Akinfenwa 80.
Ref: K Stroud (Dorset).