A controversial late winner by William Gallas earned Arsenal a 2-1 victory over Hull City in their FA Cup quarter-final on Tuesday and set up a last four showdown with Chelsea at Wembley.
The French defender flicked in a close-range header from what appeared to be an offside decision shortly after Dutchman Robin Van Persie had equalised for the Gunners.
Arsenal had trailed to Nicky Barmby's early strike and were not posing much threat until Hull buckled late on.
Hull boss Phil Brown accused Arsenal skipper Cesc Fabregas, who did not play because of injury, of spitting at the feet of Hull's assistant manager Brian Horton after the match.
"I was there, I witnessed it, he spat at his feet," Brown said at the post-match news conference, shown on Sky Sports News.
Arsenal manager Arsene Wenger said he had no knowledge of any incident.
"I cannot speak about something I haven't seen," Wenger said at his news conference.
Hull, hoping to reach the last four of the FA Cup for the first time in 79 years, started brightly and took the lead after 13 minutes when Barmby's effort deflected off Johan Djourou and evaded Arsenal's reserve keeper Lukasz Fabianski.
Arsenal, who made six changes from the side that beat Blackburn Rovers on Saturday, took a long time to respond and Barmby had another effort ruled out for offside.
As the clock ticked down Hull's resistance finally broke when Andrei Arshavin set up Van Persie, who sent a rising shot past Hull keeper Boaz Myhill.
Hull had a chance to regain the lead through Brazilian Geovanni but they were sunk when Myhill flapped at high ball played into the area and Gallas, who was stood all on his own in the six-yard area, headed the winner.
The other semi-final will be between Manchester United and Everton.