Two matches in the 2007 World Cup which led to massive disaster and major structural changes in the history of World Cup.
First of all, the 2007 World Cup reintroduced the setup which was not in place after the 1979 WorlCup. To have 4 groups of 4 teams each with less number of Group stage matches and more number of Knockout matches. Between 1983–2003 players were playing six group matches each but in the 2007 world cup they again introduced the 3 group matches formula.
Second thing was the satellite rights of the World Cup. Sony group in India had the cricket telecast rights of the 2003 world cup when India reached the finals which meant huge profits for the Sony group. So naturally they acquired the rights for the 2007 World Cup as well.
So two major matches ruined the whole world cup and the future of this format. One was India vs Bangladesh where India failed badly against Bangladesh and got out for mere 191 runs. Half of these runs were scored by Saurav Ganguly and Yuvraj Singh but they played so slowly (Ganguly scored 66 of 126 balls) that they couldn't even total 200 by the end of their innings (they got out in 49.5 overs). It was a bad decision to send Sachin at number 4 despite his constant request to let him open. This was perhaps the most forgettable world cup for Sachin Tendulkar. Similarly Dhoni scored 2 ducks in three matches, Uthappa scored 30 runs in 3 matches which worsened the cause of team India. Bangladesh was further helped by poor fielding from India and they inflicted a shocking defeat on India. Indian team made a thumping comeback against a nobody team Bermuda scoring 413 runs and winning by 257 runs. But the team again chocked against Srilanka losing by 69 runs and made a shocking exit from the World Cup. This world cup led to the end of ODI career for Anil Kumble and surprisingly the highest scorer for India Virendra Sehwag lost his opening slot as Sachin and Ganguly became the openers for the rest of the year.
Similarly fate awaited our neighbour and arch enemy Pakistan who lost against West Indies in their opening match. But shockingly they lost against Ireland who bowled out Pakistan for 130 runs and won by 3 wickets eliminating them from the World Cup. The world cup was even worse for Pakistan whose coach Bob Wulmar was found d**d in his hotel. Allegations were made of match fixing and Inzamam Ul Haq retired.
On a financial front this world cup wa shighly unsuccessful as the top 2 teams of Asia who contributed so much in revenue were ousted in the first round. Set Max and Sony lost hundreds of crores and were nearly bankrupted (interestingly that time they recovered their money by constantly re running their most popular show CID for 18–20 hours a day for about 2–3 years).
BCCI made a statement that they would make sure that such format will not be followed after this world cup and this is the same that happened. It also shows the power of BCCI in international cricket.