Grimsby progressed to the fourth round of the Carabao Cup for the first time in 24 years thanks to a 1-0 win over a youthful Sheffield Wednesday side at Hillsborough.
The two clubs pulled off the biggest shocks in round two, with the League Two Mariners upsetting Manchester United on penalties after Wednesday's youngsters embarrassed Yorkshire rivals Leeds in similar circumstances.
Jaze Kabia headed the 49th-minute winner on Tuesday as Grimsby deservedly overcame an inexperienced Owls team featuring eight academy players in the starting XI.
Around 6,000 travelling fans celebrated the success in South Yorkshire, with the home support heavily outnumbered due to a planned boycott as part of ongoing protests against under-fire owner Dejphon Chansiri.
Crystal Palace survived a scare by scraping past south London rivals Millwall 4-2 on penalties after conceding a last-gasp equaliser to draw 1-1 at Selhurst Park.
Eagles goalkeeper Walter Benitez - a summer signing from PSV Eindhoven - marked his debut by saving from Lions pair Tristan Crama and Aidomo Emakhu in the shoot-out.
Chris Richards' 72nd-minute goal looked to have booked Palace's place in the last 16 before Ryan Leonard levelled for the Championship visitors in added time.
Brentford keeper Hakon Valdimarsson atoned for a costly error by becoming the shoot-out hero as his side defeated Aston Villa 4-2 on penalties.
The Iceland international, who provides back-up for Caoimhin Kelleher in the top flight, kept out spot-kicks from John McGinn and Matty Cash before Bees substitute Mikkel Damsgaard converted the winning penalty.
Aaron Hickey's stunning 57th-minute equaliser earned Brentford a 1-1 draw at the Gtech Community Stadium after Harvey Elliott capitalised on a mistake from Valdimarsson to score Villa's first goal of the season on his full debut.
PA
