It's hard to imagine now, but physically-imposing 6' 3" centre-back Jean-Alain Boumsong was dissuaded from playing football as a child because he was too fragile. That was back in his native Cameroon, where he lived until the age of 14, and it provoked a long period of doubt which has turned Boumsong into one of the most reflective players on the circuit.

He tried his hand at volleyball, the sport his father played at international level, but even after he had grown into the powerful defender he is today, he was still pursuing a Plan B: "I hadn't played much football in Cameroon, so I didn't consider it a realistic career option. Auxerre were interested in me as a youngster, but I wanted to continue my studies so I joined Le Havre because of the university there."

Incredibly, the then 18-year-old began training to be a doctor while playing Ligue 1 football at the weekends, and when the medical school objected, he switched to mathematics and completed his degree. "It gives me a concrete qualification," he says. "So if ever my football career goes wrong, I know I can earn my living as an engineer, for example."

Not much has gone wrong with his football career so far, though. Two years after making his top-flight debut, he finally joined Auxerre in 2000 and spent four seasons in Burgundy, where he formed a formidable partnership at the back with Philippe Mexès. His flamboyant colleague earned a high-profile, if controversial, move to Roma in 2004, but many experts identified Boumsong as the real star in Guy Roux's rearguard. So it came as some surprise that he chose Glasgow Rangers as his next destination, even if he only spent six months in Scotland before joining Newcastle in January 2005.

That sudden transfer made him an unpopular figure at Ibrox and, typically, he regrets having soured what he still regards as a memorable experience. "I was disappointed with the way it all ended," he explains. "In fact, I almost felt like a thief because it was so quick. It's not in my character to leave a team midway through the season and I feel a little ashamed to have left my teammates." A rapid £8m profit for the Gers certainly helped soothe the situation, though, and Boumsong felt he needed to step up a level to improve his flagging international credentials.

It did the trick too, and he finished the 2004-05 season in France's starting eleven, even collecting the captain's armband from Sylvain Wiltord in the 2-1 win over Hungary in May. Having thought long and hard about opting to represent Cameroon before choosing Les Bleus, that was confirmation he had made the right decision. "I like the best things from both cultures and both countries, but at the time Cameroon football had a lot of problems and was not in good health," says the man whose first footballing idol was Roger Milla. "That's why I chose France, but they had just won the World Cup in 1998 and, phew!, I knew it would be difficult to get into the team."

Combining intelligence with his impressive physique, Boumsong looks a natural on the international stage. He is as thoughtful on the pitch as he is in real life, and rarely picks up a booking, all of which has led to comparisons with Marcel Desailly. "That's quite a compliment," he says. "If I have three-quarters the career Desailly had, that'd be great. When I look back at his career and see how consistent he was, I know what the benchmark is for me." It doesn't take a degree in mathematics to see that he is already on his way.