Second-seeded Stan Wawrinka was sent crashing out of the Aegon Championships second round by big-serving South African Kevin Anderson on Wednesday.
Wawrinka, who lifted his first French Open title earlier in June, saw his Wimbledon preparations spoilt in straight sets as Anderson claimed a 7-6(4) 7-6(11) victory at Queen's Club.
The Swiss saved five match points in the second-set tiebreaker and missed a straightforward forehand to take proceedings into a third set, before Anderson wrapped up the win with his 22nd ace of the match.
"It was a terrific match for me," the victorious Anderson told BBC Sport. "He's a terrific player so it means a lot to me and to do on such a great court makes it extra special.
"My serve was a big plus right from the beginning. Stan also has a good serve but I was able to return pretty well."
Anderson will next face either Guillermo Garcia-Lopez, who claimed a 6-3 7-6(4) victory over Alexandr Dolgopolov, the man who shocked 2008 champion Rafael Nadal in the opening round.
In other results, No.7 seed Gilles Simon defeated Australia's Thanasi Kokkinakis 6-4 6-2.
Kokkinakis, 19, admitted to feeling slightly star struck after spotting former Top Gear presenter Jeremy Clarkson and One Direction singer Liam Payne in the stands.
"Was the guy from One Direction here too?" he said. "Yeah, I've just got to do better than that really. I got distracted a little bit, but I looked over when I was down a set and double break. At least I saw some important faces in the crowd."
No.3 seed Milos Raonic needed three sets to get past Richard Gasquet 6-4 6-7(5) 6-1, while British No.1 Andy Murray saw his doubles challenge with partner Dom Inglot thwarted by a 6-4 7-6(3) victory for top seeds Alexander Peya and Bruno Soares.