London - Both English Premiership matches in London on Boxing Day are under threat as a result of a planned strike by underground drivers.Arsenal have sold all 60 000 tickets for their match at home to Wolves on December 26 but access to the Emirates Stadium for fans and the club's 1 000 match-day staff could be hampered if the 24-hour strike that day by members of ASLEF, the drivers' union, goes ahead."The club is fully aware of the proposed industrial action on London Underground on Monday, December 26," said a statement posted on Arsenal's website on Monday."We are closely monitoring the situation, together with all the relevant agencies...The paramount concern to Arsenal Football Club is the duty of care we have towards the Arsenal supporters, Wolverhampton Wanderers supporters, match-day employees and indeed everyone who is planning to attend this match."Any decisions or developments regarding this match will be immediately communicated on Arsenal.com."London mayor Boris Johnson is pursuing a legal challenge against the strike but if that move, or further talks, fail to halt the industrial action, Arsenal could delay the Wolves fixture by 24 hours.Chelsea's west London derby against Fulham on December 26 could also be disrupted by a shutdown of the 'tube'.Howard Collins, London Underground's chief operating officer, said on Monday: "We are in close contact with Arsenal Football Club, and others who may be affected if the strike goes ahead."We are keeping all parties informed at every step of the way and, if the strike action does take place, we will be using every channel available to keep football fans and all of our customers informed."