WATCH: Racing's Juan Imhoff gets a red for a headbutt

Racing 92's Juan Imhoff was handed a red card for a headbutt after Castres Rory Kockott was shown yellow for a bizarre tackle.

Racing 92 kept themselves in the hunt for a Champions Cup quarter-final place with a 29-7 win over Top 14 rivals Castres on Saturday.

Leone Nakarawa, Virimi Vakatawa, Dimitri Szarzewski and Louis Dupichot all went over for Racing, while Maxime Machenaud added a penalty and two conversions, and Teddy Iribaren one conversion.

However, the win was spoilt by the red card of full-back Imhoff who headbutted Castres No 9 Rory Kockott for his tackle on Iribaren.

Wayne Barnes is clearly heard telling Kockott that he was lucky he did not drop him before the video ref highlights Imhoff's use of the head.

Click on the video above to view Kockott's tackle which infuriated Imhoff.