American star Christian Pulisic will be sidelined for weeks due to a “nasty” adductor injury, dealing a blow to his Premier League club Chelsea as they push for a Champions League place manager Frank Lampard said on Friday. The 21-year-old United States captain suffered the injury prior to last weekend's FA Cup third round victory over second tier Nottingham Forest. Pulisic has scored five times in 16 Premier League appearances in his maiden season for Chelsea since joining for £58 million ($76 million) from Borussia Dortmund. However, he has not hit the target in the league since the 2-0 win over Crystal Palace on November 9 and he admitted earlier this month he needed to be more clinical in front of goal.