Brighton dumped FA Cup holders Liverpool out of the competition on Sunday as Hollywood star and Wrexham co-owner Ryan Reynolds saw his non-league side denied a dramatic win by Sheffield United in a six-goal thriller.
Kaoru Mitoma's brilliant control and finish in stoppage time to seal a 2-1 win for Brighton was another enormous blow to Liverpool, whose season is unravelling just months after they came close to winning a historic quadruple.
The Reds had led at the Amex through Harvey Elliott, but have now won just once in their past six games in all competitions.
Lewis Dunk levelled before the break for the home side and they were well worth their place in the fifth round courtesy of a moment of magic from Mitoma.
The Japanese winger cushioned Pervis Estupinan's cross into his path, flicked the ball over Joe Gomez and fired high past Alisson Becker in the 92nd minute.
"He is an incredible player who I think can play one step higher," said Brighton boss Roberto De Zerbi. "I am pleased for his goal."
Liverpool are languishing in ninth place in the Premier League, 21 points behind pacesetters Arsenal.
An FA Cup exit at the fourth-round stage leaves the Champions League as their only remaining shot at a trophy this season.
Jurgen Klopp described Brighton's 3-0 win when the sides met earlier this month as a "horror show".
And the German coach at least took some heart from his team's battling performance on Sunday.
"I am not over the moon about this performance but, again, the only thing that happened really is that we lost against a good side, who we lost to two weeks ago in a horrendous game," said Klopp. "Today was much better.
"We are obviously in a situation where we constantly want to make the final step. That's why it feels now especially bad in this moment because it didn't happen."
The hosts were without Moises Caicedo after the Ecuadoran took to social media on Friday to try and force through a move to Arsenal.
Brighton have already lost Leandro Trossard, who scored a hat-trick against Liverpool earlier in the season, to the Gunners this month.
But those absences did not show as Liverpool were left riding their luck for most of the second period.
Ibrahima Konate and Fabinho were extremely fortunate to escape red cards for challenges on Alexis Mac Allister and Evan Ferguson.
Brighton's pressure finally paid off when Mitoma struck his fourth goal in six games.
- Wrexham heartbreak -
Wrexham are the last non-league club left in the competition but were left disappointed as John Egan made it 3-3 in the dying seconds for the 10-man Blades.
The hosts could not have got off to a worse start as Oli McBurnie headed Sheffield United in front after 61 seconds.
Paul Heckingbottom's side look set for a return to the Premier League next season, but they were rocked by a pulsating atmosphere inside the Racecourse Ground.
James Jones and Thomas O'Connor struck within 11 minutes early in the second half to turn the tie around.
Oliver Norwood quickly levelled, but the momentum swung Wrexham's way once more when Daniel Jebbison was sent off 20 minutes from time.
Paul Mullin looked to have pulled off the shock of the round with a calm finish four minutes from time, only for Egan to break Wrexham hearts by turning home a corner at the death.
"Impossible is @Wrexham_AFC's favourite colour," tweeted Reynolds, who took over the club in 2020 along with fellow actor Rob McElhenney. "That was one of the most exciting things I've EVER seen.
"Thank you each and every Wrexham supporter who came out and aimed your heart at that pitch tonight."
Stoke progressed to the last 16 with a 3-1 win over Stevenage.
There were no shocks in Saturday's action, with all the Premier League sides progressing to the fifth round with the exception of Fulham, who were held 1-1 by Championship side Sunderland.
Manchester City beat Arsenal 1-0 on Friday to progress, with Derby due to take on struggling West Ham on Monday.