The surprise winner of the first round of France's rightwing presidential primary immediately came under attack Monday, with Francois Fillon's rivals slamming his radical reform agenda as "ultra-conservative" and "unworkable". Former prime minister Fillon, an admirer of Margaret Thatcher, pulled off a stunning upset Sunday, coming from behind to knock his former boss Nicolas Sarkozy out of the race and beating the favourite, Alain Juppe, into distant second. Fillon will go head-to-head with fellow former premier Juppe in a run-off Sunday that is widely expected to decide France's next leader after a prospective duel next year with far-right leader Marine Le Pen.