His rise to this level is all the more remarkable given the fact he missed out on playing between the ages of 16 and 18 due to glandular fever.
Before today's triumph, his biggest claim to fame was a close friendship with snooker star Ronnie O'Sullivan who he is now teaching to play tennis.
By around 600 places, Flanagan is the lowest-ranked player left in the tournament and his status stands in marked contrast to Philippoussis, who is a former Stella Artois champion and US Open runner-up.
Philippoussis said: "It was not a great day, I was never comfortable from the start. I held off from everything and he served well. I had never seen him play before, but it doesn't matter what your ranking is - if you come through qualifying you can play tennis."
It was a bad day all round for former Wimbledon finalists with Ivanisevic also losing in the first round. The bigserving Croatian, who will retire from tennis after Wimbledon, lost 7-6, 4-6, 4-6 to Hanescu.
In an earlier match, Slovakia's Karol Beck beat Gilles Elseneer of Belgium 6-3 6-4 and will meet Tim Henman tomorrow.
Greg Rusedski's turmoil continues after his exit at Queen's yesterday The British No2, cleared in March after a long-running nandrolone controversy, lost 3-6, 6-3, 6-4 to South Korea's Hyung-Taik Lee.
He will now take up a wildcard entry at next week's Nottingham Open but aid: "It's tough to come back at any time and this one is the most difficult. It's frustrating because my mind knows what I need to do out there, but it's not happening."
Former world No5 Daniela Hantuchova made a confident start to the DFS Classic in Birmingham with a straightsets win over Korean No1 Yoon Jeong Cho.
The 21-year-old Slovak is unseeded after plummeting to 54 in the world rankings. But she made light work of the 25-year-old Cho, winning 6-3 6-1 in just 54 minutes.
