ESPN executives had to scramble five years ago when slugger Sammy Sosa got caught with a corked bat.

A major news story was developing, but all the network had scheduled to air early the next day were replays of the previous night's SportsCenter. ESPN rushed to go live, and the results were eye-opening. Ratings shot up, even though viewers had no advance notice of the additional coverage.

ESPN has added special live programming as needed for major news events in the years since. It all culminates Monday, when the network begins airing live editions of SportsCenter from 9 a.m. to 3 p.m. EDT on weekdays.

Chris McKendry figures the demand is obvious after her recent experience during rehearsals for her role as co-anchor in the noon-3 slot. Twice in a few days, she was called into live duty, first for Tim Donaghy's sentencing, then for the baseball trade deadline.

Just when it seemed ESPN was already everywhere you turned, it's more than doubling the typical amount of live SportsCenter broadcasts each weekday, from 4 hours to 10.

Success won't be measured only in ratings, said Norby Williamson, ESPN's executive vice president for production. Instead, the gauge will be the new shows' impact on ESPN's long list of properties. Will more people view snippets of SportsCenter online during the workday now that a fresh edition airs every hour?

McKendry recalled the debate when she joined the network around the launch of ESPNEWS in 1996.

''There was a lot of fear of cannibalizing the product,'' she said. ''We found out it didn't. Instead, it made people more addicted.''

Indeed, fans can already get live coverage on ESPNEWS in the morning and early afternoon. But Williamson believes they want the SportsCenter format with its ability to delve deeper into issues.