LONDON (REUTERS) - Manchester United's Luke Shaw will miss the start of the Premier League season and could be sidelined for four weeks after suffering a hamstring injury, the club said on Wednesday.

The 19-year-old left-back, who arrived at Old Trafford from Southampton in June for around £30 million pounds (S$62 million), is yet to make his competitive debut for United.

Shaw, a member of England's World Cup squad who earned his third cap in the goalless draw against Costa Rica, missed United's final pre-season friendly against Valencia on Tuesday.

He faces a wait of up to a month to make his first start and new United manager Louis van Gaal has a selection headache following the departure of experienced left-back Patrice Evra to Juventus.

United kick off the Premier League season against Swansea City at Old Trafford on Saturday.