Barry Ferguson has condemned his nephew for his tackle in Aberdeen's 3-0 defeat by Celtic during Sunday's Scottish Cup semi-final at Hampden Park.
Lewis Ferguson was issued a straight red card on 67 minutes for a rash challenge on Celtic midfielder Tom Rogic.
The Dons were missing captain Graeme Shinnie on the day, and Ferguson is putting family loyalties to one side and refuses to defend the 19-year-old midfielder.
The Rangers legend told PLZ Soccer: "I can't defend Lewis. I know he's my nephew but it was a two-footed lunge.
"It comes down to inexperience for me. Aberdeen were missing Graeme Shinnie, who might've told him to calm down and get on the ball.
"I can't defend him, it was a sending-off. I'm sure Lewis will learn from it."
The Dons already had Dominic Ball sent off in the first half following a clash of heads with Celtic star Ryan Christie, who needed to be stretchered off.
Despite the challenge, Rogic, who replaced Christie, was fit to continue.
On the football side of things, the victory takes the Hoops - who have an 11-point lead over Rangers in the Premiership - to within 90 minutes of a potential Treble Treble.