LONDON - 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. After the match, Arsenal's club captain Cesc Fabregas issued a strongly worded denial after Hull manager Phil Brown had accused him of spitting at assistant boss Brian Horton. "I categorically deny that I spat at anybody after the match," Fabregas, who did not play because of injury, said in a statement on the Arsenal website. "I have never done this in my whole career on the pitch, so why would I do it when I am not even playing?" HULL LEAD 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 will be between Manchester United and Everton.