Arsenal announced former Paris Saint-Germain coach Unai Emery as their new boss on Wednesday, handing him the daunting task of revitalising a club that has slipped well behind their Premier League rivals. The Spaniard, who won the domestic treble with this season, emerged as the shock favourite to replace Arsene Wenger earlier this week after it had appeared former. Arsenal will be wary of the turmoil at Manchester United after the departure of long-serving manager Alex Ferguson in 2013 but said the choice of Emery was unanimous.