Nadal, the 2008 and 2010 champion, slumped to a 7-5, 3-6, 6-4, 6-4 second round defeat against the world number 102, who cracked 13 aces and 58 winners on Center Court.
It was the 29-year-old Spaniard’s first ever defeat to a qualifier at a Grand Slam and came in the aftermath of losing his French Open crown where he had been champion nine times.
The loss followed his 2012 second round exit to world 100 Lukas Rosol, a first round beating by the 135-ranked Steve Darcis in 2013 and last year’s fourth round defeat to Nick Kyrgios, who was at 144.
Down at his lowest ranking for a decade—10th in the world— Thursday’s defeat was yet another sign of the great Spaniard’s game being in a worrying state of decline.
“I lost. Sad today for that, obviously,” said Nadal, who was also runner-up at Wimbledon in 2006, 2007 and 2011.
“But end of the day, that’s sport. Good moments, bad moments. Obviously today is a bad moment for me. Just I need to accept these kind of things that can happen.
“I am a good loser but I will keep going. It’s not the end. Life continues, my career, too.”
For Brown, who once drove to tournaments in a camper van to save money, it was his second win against Nadal, having beaten him on grass at Halle in 2014.
“I had actually never been on Center Court before,” said the 30-year-old.
“They asked me before the match if I wanted to go on the court. I didn’t know what was going to happen, so I just said I’ll just go on when I play.
“I thought it might freak me out a little bit but, I don’t know if it was the match in Halle, it felt very familiar.”
Brown will next face Serbia’s Viktor Troicki.
There were no such problems for former champions Roger Federer and Andy Murray, who swept into the third round.
Seven-time winner and second seed Federer eased to a 6-4, 6-2, 6-2 win over Sam Querrey of the United States, the world number 36.
The Swiss fired 32 winners and hit just nine unforced errors in an 86-minute Centre Court stroll and will face Australia’s Sam Groth for a place in the last 16.
Third seed Murray, the 2013 champion, was equally dominant, taking just one minute longer than Federer to see off Robin Haase, the world number 78 from the Netherlands, 6-1, 6-1, 6-4.
The Briton smashed 25 winners and goes on to face experienced Italian Andreas Seppi.
Royal sweatband souvenir
Murray caused some amusement when he threw his sweatband into the crowd, where it hit the head of All England Club chairman Phillip Brook—who then handed it as a gift to Prince Charles’ wife Camilla, the Duchess of Cornwall, who was sitting next to him.
“Normally you see who catches it. Then the Duchess opened up her bag and my wristband was in there, so he obviously had given it to her,” said Murray.
Czech sixth seed Tomas Berdych, the 2010 runner-up, defeated French wildcard Nicolas Mahut 6-1, 6-4, 6-4.
Women’s defending champion Petra Kvitova reached the third round with a 6-2, 6-0 win over Japan’s Kurumi Nara, at 1.55-metre (five feet, one inch) tall, the smallest player in the world top 100.
The Czech fired 10 aces and 23 winners and has lost just three games in two matches. Second seed Kvitova next faces Serbian 26th seed Jelena Jankovic.
Fifth seed Caroline Wozniacki made the third round with a 6-1, 7-6 (8/6) win over Denisa Allertova, the world number 83 from the Czech Republic.
The women’s draw opened up even further when Russian eighth seed Ekaterina Makarova, a quarter-finalist in 2014, went down 6-2, 7-5 to unseeded Magdalena Rybarikova of Slovakia.
Before this tournament, world number 65 Rybarikova had never won a match at Wimbledon in seven years.
Makarova joined third seed Simona Halep, seventh seed Ana Ivanovic and Carla Suarez Navarro, seeded nine, in failing to get beyond the second round.