Spanish qualifier Cristo Reyes continued his run at the PDC World Championship, while Phil Taylor and Adrian Lewis progressed.
Reyes, from Tenerife, downed 20th seed Kevin Painter 4-3, winning three consecutive sets to pull off another upset at Alexandra Palace.
The Iberian qualifier became the first Spaniard into the last 16 of the tournament, his run also seeing him defeat 13th seed Wes Newton in the first round on December 18.
Reyes said he never gave up against the more-experienced Englishman.
"I will always fight right until the end, even though I was 3-1 down I was always going to fight until the last dart," he said.
"Until the referee calls the final shot I always think I can win and until the last dart goes in I will always keep going - that's the way I always play and that won't change.
"We have flights booked for tonight so we'll have to go and try to change them now and try and book the hotel for an extra few days so I can stay here and prepare for the next match in a few days - but that's a happy thing for me to do."
Of the six matches, Reyes' result was the only upset of the two sessions in London on Sunday.
Second seed Taylor is yet to drop a set in the tournament, after his 4-0 rout of Wales' Mark Webster.
Webster beat Taylor at the 2011 event but the 16-time world champion got his revenge - losing just four legs in 16 as he cruised into the third round.
Third seed Lewis was forced to sweat a bit, as he outmuscled promising Englishman Keegan Brown 4-2.
Lewis, a two-time champion, came from 2-1 down, and won deciding legs in each of the final three sets to advance.
Dean Winstanley won a marathon all-English contest with Darren Webster 4-3, winning the deciding set 4-2 in a tie-break.
Belgium's Kim Huybrechts won a topsy-turvy battle with Ian White 4-3, coming from behind to win the final two sets to deny the Englishman.
Andy Hamilton, the 12th seed, overcame a sluggish start to oust Australian Kyle Anderson 4-2.
Anderson led 2-1 early but Hamilton lost just one leg in each of the following three sets to seal his progression.