San Francisco - Few world-class companies are so closely associated with one man as Apple is with Steve Jobs.

But Tim Cook, the man who is scheduled to step into his shoes at least during his six month medical leave, is credited by many insiders as being an operational genius who deserves much of the credit for Apple's incredible success over the past ten years.

The 48-year-old Alabama native came to Apple in 1998 after working at IBM and Compaq, and turned Apple's manufacturing and supply chains into the envy of the tech world. A workaholic and fanatical cyclist in his spare time, Cook is reported to keep his energy levels up with a constant diet of sports bars.

According to Bloomberg financial news service, Cook has actually been running the company for several years, with Jobs filling a role as the public face of Apple. Cook formally filled in for Jobs in 2004 when the Apple founder underwent surgery for pancreatic cancer.

Cook's success in that role earned him a promotion to chief operating officer and made him the company's top paid executive. His relentless quest for efficiency in every facet of the business is credited with the company's amassing a cash haul of over 24.5 billion dollars

"Tim runs Apple and he has been running Apple for a long time now," said Michael Janes, the former general manager of Apple's online store in an interview with Wired. "Steve is the face of the company and very involved with product development, but Tim is the guy who takes all those designs and turns it into a big pile of cash for the company."

Janes also said that Cook played a key role in the design process of Apple's most successful products, including the iPod, iPhone and Macbook laptops.

"Steve didn't make up the iPod, iPhone or iTunes all by himself," said Janes. "To get the manufacturing right you have to get the design details right and Tim has been there through the whole development process." dpa