Chelsea had lead from early in the second half when Lee Cattermole bundled the ball into his own net, with goal-line technology playing a part in deciding it was a goal:
Borini, who was a 74th minute substitute for Adam Johnson, then turned provider to set up Ki Sung-Yueng for Sunderland‘s winner in the 118th minute and knock Jose Mourinho’s side out of the competition.
The goal was Borini’s second for the Black Cats, after scoring a stunning goal against Newcastle in October.
Borini was signed from Roma in July 2012, having had previous spells at Chelsea and Swansea but has made just 20 first-team appearances for Liverpool, scoring twice.
Despite the 22-year-old being sent on-loan to Sunderland for the season, Brendan Rodgers last month insisted he has a bright future at Anfield.
“Fabio is a young player who has been unfortunate,” Rodgers was quoted in the Metro as saying. “He got injured early on and was out for a period of time. That first year for a lot of players at a big club is difficult.
“He was a player who I felt needed games. He’s got talent and you saw that with his goal the other day [against Newcastle].
“I just felt this year, with us having limited games, that I had players, especially the young ones, who weren’t going to play so much. I needed to plan forward in order to get these players to maximise their potential for Liverpool.
“Sometimes that will mean going out and getting games. And with the likes of Fabio that’s why he’s gone to Sunderland.
“He’s definitely got a future here. He’s a talented young player and one who, over the next few years, will hopefully develop well.”