It is not the first time this season McIlroy has been in trouble for such an incident, with the world number one hurling his three iron into a lake at Doral during the WGC-Cadillac Championship in March.

And it is not the first time he has thrown a club in anger at Wentworth, doing so in 2012 on his way to rounds of 74 and 79.

“Acceptance of bad shots is the thing I have been doing so well and I feel like my patience was wearing a bit thin,” McIlroy said. “I just need to stay in control of my emotions because I feel like that’s one of the things... if I’m a little tired or a little fatigued mentally, I’ll start to be hard on myself and start to get down on myself.

“I played okay. There weren’t really any aspects of my game I thought were really good, but at the same time I don’t feel any aspect of my game was really off.”

Molinari, whose brother Edoardo retired with a wrist injury after playing 16 holes in eight over, was joint second in the Spanish Open last week and has an excellent record at Wentworth, having finished seventh, ninth and seventh in the last three years.

“Any time you shoot 65 round here is a great score but unfortunately they don’t give you the trophy after the first day,” Molinari said. “I need to keep my head down, play well on Friday, Saturday and Sunday and see if that’s going to be enough.”

Molinari enjoyed a two-shot lead over former European number one Robert Karlsson, with England’s Chris Wood, Scotland’s Marc Warren, former US PGA champion YE Yang and Spanish pair Miguel Angel Jimenez and Jorge Campillo all four under.

Two-time winner Luke Donald recovered from two over par after 10 holes to record a 70, while Spanish Open winner James Morrison was four over after 10 before covering the last seven holes in five under.