Chelsea are facing a battle to keep Arsenal, Liverpool, Manchester United and Tottenham target Juan Mata at Stamford Bridge with PSG set to launch a £40m bid. Mata has endured a mixed start to the season, often being left out of the first-team by Jose Mourinho since he returned to the club as manager. According to reports in France, the big spending Ligue 1 champions are huge admirers of Mata, 25, and want to test his resolve to staying at the Blues by offering him a regular starting berth. PSG failed in their attempts to bring Mata to the Parc des Princes in the summer, but manager Laurent Blanc is eager to strike a deal with Mourinho for the playmaker in the new year. Mata is desperate to cement his place in Spain's World Cup squad ahead of next summer's finals in Brazil and the promise of first-team football may prove to hard to turn down. Arsenal, Liverpool, United and Spurs have all been monitoring Mata's situation with a view to stepping up their interest in the January transfer window. News of PSG's bid is likely to perk the intent of the Premier League quartet in their attempts to secure a deal for Mata.