 Complete the following phrase:  Chelseas emergence as title challengers put an end to Arsenal and Manchester Uniteds domestic duopoly. The West London club won back-to-back league titles in 200405 and 200506 under José Mourinho, at a time when Arsenal and United underwent a period of transition. Vieira and Keane had left their respective clubs by the end of 2005, while Ferguson came under intense scrutiny over his management. Nevertheless, he guided his team to Premier League success in 200607, and won a further four league titles. At Arsenal, Wenger oversaw the clubs relocation to the Emirates Stadium and made the decision to prioritise it over strengthening the squad. The club sold several experienced players, replenishing them with younger talent. The 2005 Cup win was their last piece of silverware until 