Talks are due to be held on Friday in a bid to avert the worst week of strike chaos on the Tube for years.It came as Arsenal warned 60,000 fans due to attend the FA Cup tie with Liverpool, which kicks off at 4.30pm on Sunday, that there would be no Piccadilly line services to get them home.Transport for London said it would be hosting talks with RMT leaders, though there was little optimism of a last-minute breakthrough.