Watch a full replay of the Darley July Cup at Newmarket plus reaction from winning connections.
Fallon, son of former champion Kieren, was the leading apprentice last season and was having just his second ride at the highest level aboard the Roger Teal-trained victor.
He made a bold move over two furlongs from home on the four-year-old, and had a length and a quarter to spare over the field.
His father famously never won the Group One and neither has Frankie Dettori, who chased him home on Denis Hogan’s Irish raider Sceptical.
Golden Horde, the 2-1 favourite, was back in third for Clive Cox, but it was Oxted (12-1) who wrote his and his young jockey’s name into the history books.
Fallon, riding in just his second Group One after finishing unplaced on Les Hogues in the 1000 Guineas, is still an apprentice but was unable to use his claim in such exalted company.
Oxted won the Portland Handicap last September, but reappeared this year with a win in the Group Three Abernant Stakes.
He was taking another big step up in grade but handled it with aplomb, always looking in control down the centre of the track for his young jockey.
Golden Horde had the seemingly preferred position on the rail, but had no answer to Oxted running into the dip and it was Sceptical, who also went close at Royal Ascot, who chased home the impressive winner.
Fallon said: "I'm speechless. I was just a passenger on a very good horse today. Mr Teal and his team have done a very good job with him.
"I can't believe I'm a Group One-winning jockey as an apprentice, never mind such a young age. I owe Roger so much for keeping faith with me.
"The feel he gives you this year, I couldn't tell I rode him last year, he feels a different horse
"He's wintered very well. I finished second on him here before he won the Portland, so we knew he'd handle the dip.
"There was a bit of pressure, but I'd spoken to my dad beforehand, my jockey coach Michael Tebbutt and my boss Mr (William) Haggas, so I'm very lucky to have the support around me.
"Dad just told me to jump out in a straight line and kick going into the dip and then see what's underneath me. What a horse.
"I've got a picture at home of us winning the Abernant, I'll have to get a bigger one of us winning the July Cup now!"
Fallon was not getting too carried away with his win and added: "You have got stay level headed in this game as one moment you can be up, one moment you can be down. I'm going to celebrate tonight with family and tomorrow is another day.
"We still live together (with Kieren). Tonight will be interesting, but I will definitely wind him up. He is very proud. He has helped me a lot this year. He was going to move to America, but he has stuck around to look after me and I can't thank him enough."
Teal was also winning his first Group One and could not hide his delight.
Teal said: "It's no surprise at all. We worked him last week and the lad who rode him said 'he wins the July Cup'.
"I said to Cieren to keep it simple as there had been winners coming down the middle the last couple of races.
"We knew Golden Horde would go forward and I said to just take a lead off him and attack him up the hill.
"He put the race to bed and won it nicely I thought.
"I've had a lot of questions asking why we were still using Cieren as he couldn't use his claim, but he's just gelled with this horse and if it's not broke, don't fix it.
"I said to the owners we couldn't take him off until he got beat on him. Cieren is inexperienced but he's very calm.
"Haydock is on the agenda (Sprint Cup) and there's a race in Deauville (Prix Maurice de Gheest), but we'll see how he comes out of today. I'm just going to go and get drunk - that's my plan!"
Fallon's father was understandably overjoyed his son had registered such a big victory so early in his career.
"He's got it - I know he's got it. It was difficult for the young lads to get going again (after lockdown), but he's had a couple of decent winners now and when you're on a roll, things fall your way," he said.
"He's got so much confidence - I wish I had half his confidence when I was riding.
"William has done so much with him behind the scenes. He has sent him to Australia and he has sent him to America. He's doing everything to get him where needs to be at.
"He works hard and he's dedicated, but without William he wouldn't be having this success. He's done a great job with him."Get your free Racing TV fleece - the latest in our range of high-class Racing TV merchandise! Click here for more details.
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