The Sun with 2.04m unique visitors has been shoved into the number three slot and is followed by News International sister site The Times Online with 1.9m, according to the latest figures from Nielsen//NetRatings.
However, Guardian Unlimited has maintained its lead over the last 12 months as the most popular national UK newspaper online with 2.7m unique visitors, which is equal to one in every 12 Britons active online.
The data shows the Telegraph with 2.07m and The Daily Mail with 1.4m, which is rooted in fifth place, are the fastest growing among the Top 10 while The Sun and the Daily Mail are the most engaging online.
As the Financial Times with 303,000 unique visitors wrestles with changes to its subscription model it is beaten by the Scotsman, which has 657,000.
The figures also show that UK's national newspapers online are growing at three times the rate of overall internet growth
Overall, 7.4m or 23% of Britons online visited at least one of the ten most popular national newspaper websites.
Alex Burmaster, European internet analyst at Nielsen//NetRatings, said: "While the Guardian and Daily Mail have consistently remained the most and fifth popular, respectively, over the last year the battle for the places in-between has see-sawed between the Sun, Times and Telegraph.
"August is the first month of 2007 not to see a Guardian/Sun one-two, with the Telegraph coming into second spot -- being ahead of both the Sun and the Times for the first time."
Unique Audience (000's)/Active Reach
1. Guardian 2,677 /8.4%
2. Telegraph 2,079 / 6.5%
3. Sun Online 2,049 / 6.4%
4. Times Online 1,912 / 6%
5. Daily Mail 1,434 / 4.5%
6. Daily Mirror 721 / 2.3%
7. Independent 681 / 2.1%
8. Scotsman 657 / 2.1%
9. Financial Times 303 / 1%
10. News of the World 297 / 0.9%