The winger was shown a straight red card by referee Anthony Taylor for shoving Jan Paul van Hecke onto the turf after chasing the ball.
Newcastle had a one-man disadvantage for eight minutes as Tariq Lamptey was also given his marching orders for a second yellow card.
However, Gordon's dismissal quickly raised questions about whether or not he'll be able to play against Liverpool in the Carabao Cup final.
Eddie Howe's will side travel to Wembley on March 16 with the chance to win a major trophy for the first time since 1955.
Will Gordon miss the final?
Gordon will rue his sending off even more as he will MISS the Carabao Cup final.
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He is likely to be given a three-match ban for violent conduct and be absent against West Ham and Brentford either side of Liverpool.
The 24-year-old was crucial on their journey to Wembley as he scored in both legs against Arsenal in the semi-finals.
However, he will miss a second Carabao Cup final with Newcastle after losing his cool against Brighton.
Gordon missed the 2-0 defeat to Manchester United in 2023 having played in the competition for Everton earlier in the season.
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Newcastle could also be without their star striker Alexander Isak, who appeared to pick up a slight injury and was substituted.
Should the Magpies be without both of their key men, the Liverpool will surely fancy their chances of winning at Wembley even more.
Sunday's FA Cup drama at St. James' Park saw Newcastle take the lead with an Isak penalty.
Yankuba Minteh made it 1-1 just before the break, before both sides fell down to ten men before the full-time whistle.
Fabian Schar thought he sent Newcastle to the quarter-finals with an excellent finish but the goal was ruled out for offside.
The winners of the tie will join Aston Villa, Crystal Palace, Preston North End, Bournemouth and Manchester City in the last eight.