Ekaterina Alexandrova made light of her grand slam inexperience to send Ana Ivanovic sliding out of Wimbledon.
The 21-year-old Russian qualified for one of the majors at the first attempt last week, and made an immediate impression on the big stage with a 6-2 7-5 victory on Court 12.
Serbian Ivanovic, the 23rd seed, had her best Wimbledon result when reaching the semi-finals in 2007 but has struggled to make an impression in recent years.
For Alexandrova, the world number 223, each result in her Wimbledon run marks a new career high.
Even with Sterling depreciating after Britain voted to leave the European Union, the £50,000 she is now guaranteed for reaching round two should top her entire career earnings to date.
In the second round of qualifying Alexandrova won a deciding set 14-12 against Stephanie Vogt of Liechtenstein, before being extended to 13-11 in a decider by British player Harriet Dart when securing her main-draw place.
Ivanovic became the highest-profile early casualty on day one of the championships, with five-time champion Venus Williams, Madison Keys and Samantha Stosur among those winning through to the second round.
Veteran eighth seed Williams fended off tenacious Croatian Donna Vekic on Court One, finally edging their clash 7-6 (7/3) 6-4, while fellow American Keys joined her in the last 64 as the ninth seed swept aside Germany's Laura Siegemund 6-3 6-1.
Australian Stosur beat Poland's Magda Linette 7-5 6-3, and 2013 Wimbledon runner-up Sabine Lisicki eased to a 6-1 6-3 win against US player Shelby Rogers.
Williams lost in the fourth round last year to sister Serena, the eventual champion.
Vekic had chances to take the opening set from her on Monday but 36-year-old Williams stuck to her task.
"I guess that's where experience sets in," Williams said.
"You've got to enjoy the battle because that's what it is every single time you walk onto the court.
"You only live once and you have to enjoy it and you have to do it while you're still fairly young. I'm still fairly young. You have to just live in the moment and when it's over, it's over."