In the 24 hours from early Wednesday to early Thursday, users downloaded 8.75 million copies of the new browser, an uptick from the 7.1 million logged by Firefox 4 its first day.

Last week's one-day tally broke the record established by Firefox 3.0 in mid-2008 when that browser was downloaded more than 8 million times within 24 hours. Then, Mozilla ran a "Download Day" campaign that resulted in a certified .

Mozilla launched the final version of Firefox 4 around 6:30 a.m. PT Tuesday after more than a year of development.

Although Firefox 4's downloads bested Firefox 3's record, the achievement won't be official. In 2008, a Guinness representative monitored Mozilla's download servers to audit the number; no on-site official was present at Mozilla last week, a company spokeswoman said.

Firefox also thrashed Microsoft's Internet Explorer 9 (IE9) on the download count. Last week's 8.75 million for Firefox 4 was almost four times the 2.4 million Microsoft touted the week before as the 24-hour count for IE9 when it .