After several bad days in the opening week, the Australian turned his fortunes around 180 degrees with the stage 9 victory on a cold and rainy Sunday in the Alps and is now second overall to Tour de France leader Tadej Pogačar (UAE Team Emirates).
"It's mind-blowing," O'Connor said in the post-stage interview. "It's what you dream of - it's so fulfilling and there's so much joy. I've managed to control myself now - compared to when I crossed the line.
"I'm just loving every single moment. I'm so happy for AG2R-Citroën, they've had so much faith in me this year. It's been so clear how much happiness it's brought to me and the team, and now also a win. It's special."
The 25-year-old wasn't planning to go on the attack but says he just bridged across and took it from there. The move went clear after the day's second climb of five, the Col des Saisies, after the intermediate sprint, and was quickly whittled down from a large group that had gained six minutes to a handful of riders fighting for the mountain classification points.
The group contained Wout Poels (Bahrain Victorious), Sergio Higuita (EF-Nippo), Nairo Quintana (Arkea Samsic), Lucas Hamilton (BikeExchange) and O'Connor, who was tailed off briefly on the descent of the Saisies and again on the Cormet de Roselend.
"I actually wasn't meant to be in the break - but there was a big group and I just crossed to it and was just waiting," O'Connor said. "I didn't really know what to do, I didn't know if I should play cool but when I heard we had three minutes, four minutes, five minutes - it's a great opportunity both to gain time on the GC and then I knew on a long day like this I could always win at the end.
"I was blowing pretty hard on Tignes. It was a mad stage. Conditions were atrocious - maybe I should be descending a little better next time - that would have saved a lot of energy," he joked.
O'Connor made it back up to Quintana, then was left with only Higuita for company on the final climb. With still 17.5km to go, O'Connor put in his move. He started with 6:45 on the Pogacar group and crossed the line victorious with still six minutes on the maillot jaune.
"I was actually scared that Tadej was going to explode from behind and chase me down when the road got hard. But I heard the time gaps and I knew for a long time that if I stayed steady and didn't cramp, I could win the stage," he said.
"I had faith the whole time and it was just about making sure I didn't panic. Because as soon as you think 'I'm going to win a stage in the Tour de France' all sorts of things happen to your mind, your lungs, your heart. It'll make your heart stop - it definitely made my heart stop just before.
"It's always a dream. Just to be here in the first place is already the first dream. To achieve this today - it's a testament to everyone who's put faith in me over the years, my fiancé, my parents, my best mates back in Australian, my friends in Andorra and Girona, it's been a wild ride."
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