LONDON, Aug 30 (Reuters) - Manchester United will need newsigning Robin van Persie to shoulder the goal-scoring burdenwhen they travel to promoted Southampton in the Premier Leagueon Sunday (1500 GMT) without the injured Wayne Rooney. Former Arsenal striker Van Persie scored on his first startfor United in the 3-2 comeback win over Fulham last weekend andmanager Alex Ferguson was delighted with the way the Dutchmanlinked up with fellow new signing Shinji Kagawa who was also ontarget. "I was pleased with both of them. ... More...