EastEnders' Alfie Moon is set to lose his cool with Derek Branning when he discovers the truth about Kat's affair.
Queen Vic landlord Alfie, played by Shane Richie, vents his anger on the Walford bad boy (Jamie Foreman) and punches him in the face in scenes to be shown on Friday, after he's unveiled as Kat's mystery man.
A BBC spokeswoman said: "After finding out the truth about his wife's affair, Alfie throws everyone out of The Vic. However, it is not long before Derek arrives to speak to him but rather than help the situation, Derek maliciously makes things worse.
"Losing his temper, Alfie hits Derek and tells him never to step foot in his pub again."
Roxy Mitchell (Rita Simons) tries to comfort Alfie when he's left heartbroken over Kat's (Jessie Wallace) betrayal.
"Alfie's world begins to crumble with only Roxy there to support him," the spokeswoman added.
The Kat infidelity storyline has gripped viewers of the soap, with several names in the frame in the storyline which has been running since the summer.
It is rumoured EastEnders bosses are saving the biggest cliffhanger until Christmas Day with Derek meeting a grisly end at his brother's Max own hands.