Louis van Gaal has told Wayne Rooney he must relax if he is to be a successful leader of Manchester United.

Van Gaal takes charge of his first competitive match as United boss today when Swansea come to Old Trafford.

It will also be the first time Rooney has led the team out as United's full-time captain. He was made club skipper on Tuesday night after the 2-1 win over Valencia.

Rooney wore the armband in the friendly, but he put in a sub-par performance.

Van Gaal believes Rooney has the potential to be an excellent United captain, but the Dutchman thinks the striker must not be overawed by the responsibility.

He told reporters he said to Rooney after the Valencia Game: "Maybe it was too much for you as a captain."

But he added: "I said to him 'let it fly', because when we were in the US, he scored a lot of goals, and made a great amount of assists."

It was Rooney's workrate and application in pre-season that won him the honour of following in the footsteps of club greats such as Sir Bobby Charlton, Bryan Robson and Eric Cantona.

But before he handed Rooney the armband, Van Gaal reminded the player - who has had bouts of ill-discipline in the past - he must be a fine ambassador for the club away from the field as well as on it.

Van Gaal enjoys a good relationship with Robin van Persie, who skippered Holland under the United boss at the World Cup, so Rooney's appointment as United captain came as a surprise.

Van Persie even missed out on the vice-captaincy, which went to long-serving midfielder Darren Fletcher.