Former Linfield manager David Jeffrey saw his Ballymena United side beat his old club 4-1 in Wednesday night's League Cup match at the Showgrounds.
It was the first time Jeffrey had come up against Linfield since taking over at Ballymena in March.
Premiership champions Crusaders needed two late goals to beat bottom club Portadown 4-3 at Shamrock Park.
Holders Cliftonville trounced minnows Annagh United while Dungannon, Glenavon and Coleraine also went through.
Carrick Rangers went through by winning at Armagh City and Warrenpoint overcame Ards after extra-time.
The win for Ballymena will capture the headlines because of manager Jeffrey but United pair Johnny McMurray and Cathair Friel deserve their share of the spotlight for some superb goals.
After Jimmy Callacher had given Linfield the lead, McMurray ran through to fire a fine finish past keeper Roy Carroll.
Friel's superb strike put Ballymena into the lead and things got worse for Linfield when Ross Gaynor was sent off. He received a second yellow card from referee Raymond Crangle for diving.
McMurray then got his second of the night with a brilliant lob and Willie Faulkner snapped up a fourth for Ballymena.
Jeffrey won 31 trophies during his 17 years in charge of Linfield between 1997 and 2014.
Premiership champions and leaders Crusaders looked to be in trouble at Portadown as they trailed 3-2.
But Paul Heatley and Michael Carvill scored two late goals to send Stephen Baxter's men through.
Aaron Haire had earlier netted twice for the Ports with Stephen Hughes making it 3-1.
David McDaid scored a hat-trick as Cliftonville, winners of the cup for the last four seasons, trounced Championship club Annagh United.
Daniel Hughes scored two and Stephen Garrett got the sixth for the visitors to the Tandragee Road.
Premiership strugglers Carrick got a much-needed win with goals by Stephen McCullough and TJ Murray earning a 2-0 win away to Armagh City.
Stefan Lavery and Jamie Glackin scored two each as Dungannon Swifts hammered Balllinamallard 6-1 at Stangmore Park.
Irish Cup holders Glenavon progressed by beating H&W Welders 4-2, Ciaran Martyn, Guy Bates (2) and Andy Hall getting their goals.
Former Glentoran player John McGuigan scored a hat-trick as Championshjip club Warrenpoint Town beat last year's beaten finalists Ards 4-2 after-extra time.