Graeme McDowell celebrates. Picture via ten-golf.comRory McIlroy compares Ian Poulter’s Ryder Cup personality transformation to Bruce Banner and The Hulk. But Graeme McDowell’s off-course manner also clashes with his steely determination when they big prize is in sight.

Just ask Pedro Fernández, the former basketball player who was José María Olazábal’s buggy driver and general factotum during that memorable Ryder Cup at Medinah.

The Spaniard had a privilged view of the European locker-room in Chicago and he explains on the excellent Spanish golf website that he was surprised how different McDowell’s off-course personality was to his warrior image on it.

“The first thing that springs to mind with McDowell is the the image of a warrior type with tons of character, dripping with charisma, friendly, chatty… What else could you think when you look back at how he won the US Open at Pebble Beach in 2010 and the Ryder Cup at Celtic Manor. Or Sunday’s victory in Woods territory once more. He played superbly even though he’s been going through a bit of a slump.

“But off the course my perception of G-Mac is quite the opposite, especially after spending a week with him during the Ryder Cup at Medinah. He’s incrediby humble, discreet, reserved… I don’t think I spoke to him for more than 15 minutes all told during the entire seven days. You’d hardly know he was in the locker room.

“He’s a serious guy, always with his game face on when he’s practicing or playing. He’d give you the impression that he’s very shy. The way he dresses is very normal. If he walked down the Gran Vía on a Saturday afternoon, you’d never notice him. And if he was pointed out to you, you wouldn’t believe it was him. He doesn’t have the aura that McIlroy, Poulter or Sergio exude.

“The most surprising thing of all is that taking all this into account, he’s a matador on the golf course - brave to the point of reckless. He just transforms himself when he steps on that first tee. It’s a mutation that’s worthy of scientific study.”