THE relationship between a top player and his caddie can be a fraught one, one of them having to kowtow to the other and not really knowing from one day to the next if he is going to keep his job. The sack, it would seem, is simply an occupational hazard.

All of which makes the partnership that Luke Donald has with his caddie particularly interesting when you consider that, for the past four years, his elder brother, Christian, has fulfilled the role. How then does it work for them? Christian, who at 33 is six years older than Luke, was working as a club professional in Marlow, Buckinghamshire, when his brother suggested that it might be a good idea to try his hand at caddying for him in his first year as a professional on the US tour.

Yet, speaking in Beijing, where they are to be found this week at the Johnnie Walker Classic, the brothers admitted that the first few months were not easy as they adapted to spending more time together than in years and, more importantly, establishing a working relationship.

They are both strong-minded, strong-willed individuals, but whatever way you look at it, one has to do the other’s bidding. “We lived together in Chicago, would room together on the road, and would go out to dinner every night,” Luke said. “It became too much and we got on each other’s nerves.

“Chris also had to learn to be a good caddie. You have to learn the ropes, to know when to speak up and when not to. The one thing he had going for him was that he knew my game already, knew the shots I like to hit and how far I hit the ball. And that is what was good about our relationship.”

They soon decided not to share the same room on tour and, in the past six months, Christian has bought his own place — an apartment in the same building in Chicago, where Luke attended university, but a few floors below. They have made a conscious effort to spend less time together and it seems to be working well.

“When I came to America, it was all very foreign to me,” Christian said. “I was relying on Luke [who had more pressing matters on his mind in what was a difficult rookie season] because he had been living in America. But once I started meeting people and making friends, things got a lot better.”

Naturally reserved, it is easy to believe them when they say they did not argue when it came to getting down to work, although Luke admits that, even now, one of their biggest mistakes is that they do not communicate enough. That said, how easy is it to live life in a younger brother’s shadow?

“There’s no feeling of Luke being the boss,” Christian responds, “but if he wants something done, there are no arguments. We’re there to do a job, to try to get Luke to shoot as low a score as possible. Obviously I’ve got Luke’s best interests at heart and he knows he’s got someone that wants the best for him.”

As two of four children (they have an older brother and a sister), they got on well together and developed a passion for golf. Because of his extra strength, the elder brother would win their early encounters, but as soon as Luke could hit the ball as far, the tables started to turn.

“I realised early on how good he was because he never missed a shot,” Christian said. “We had some good matches. When he was 15, he was playing off a handicap of one and I was about four, but he was more consistent and wouldn’t have the slumps that I had.”

And so to the present. Do they ever quarrel over decisions on the course? “Not really. Luke’s very good and is almost his own caddie,” Christian said. “He knows what club to hit and what shot to play, and he’s virtually always right, although I will always say what I think.”

He added: “When you work for a really good player, you’ve got the chance to make it pay; financially it’s very rewarding. I’ve still got my PGA status and could always go back to what I was doing before. But at the moment I love doing what I’m doing.”

How easy, then, was it to remain detached when Luke was in serious contention at the Masters and the Players Championship in recent weeks? “In one respect it’s harder because you’re connected. If things are going well, it’s fantastic, but you feel the pain as well if things go badly. It’s quite difficult and I feel for him more,” Christian said.

Fully settled to his new life, Christian now spends most of his time with the other caddies. And here’s a thing: so does his younger brother. “They’re a lot more fun and have better stories,” Luke said with a smile before gathering up his things and heading off to the practice ground. There was work to be done.