Mac Allister's brother Kevin was sent off for 'piggybacking' on the rival, leaving fans stunned

ALEXIS MAC ALLISTER's brother was sent off for a bizarre moment during the Brussels derby.

Kevin Mac Allister played for his club Union SG against local rivals Anderlecht in the quarter-finals of the Belgian Cup.

Kevin Mac Allister was sent off for a bizarre challenge in Union SG's match with AnderlechtCredit: Rex

Kasper Dolberg was through on goal for AnderlechtCredit: X/RTLsportsbe

Mac Allister jumped on the striker's back to prevent him from scoringCredit: X/RTLsportsbe

The Argentinian took no chances by letting Dolberg get a shot awayCredit: Rex

Mac Allister's attempt to climb Dolberg's back landed him on the ground and as a result he was dismissedCredit: AFP

Because both Union SG and Anderlecht are based in the Belgian capital Brussels, drama often ensues when the two meet.

And with the stakes high, it appears Kevin Mac Allister, 26, lost his mind and made a rash decision.

The Argentinian was shown a straight red card in the 32nd minute of the cup match when he appeared to jump on the back of Anderlecht striker Kasper Dolberg.

Dolberg ran through on goal when Mac Allister felt he had to intervene to prevent what would have been a clear scoring opportunity.

The defender's intervention turned out well for his team, as Anderlecht received a free kick instead of a penalty after the incident.

Fans were quick to respond to the unusual broadcast on social media, often saying it was a great intervention.

One wrote: “Have you ever seen a better tackle?”

While another added: “An absolute elite red card for Kevin Mac Allister against Anderlecht tonight.”

A third joked: “Leave him alone, he just wanted a piggyback!”

And a fourth voted in writing: “11/10 wrong. No notes.”

Union SG may think this was the right decision after all, as they still managed to win the match 2-1 without Mac Allister on the pitch.

An early goal from Dolberg could have meant the difference between advancing to the next cup round or being eliminated.

Union SG will now play Club Brugge in the semi-finals of the competition next month.

Although Kevin Mac Allister would only be able to watch it from home with his suspension.