Kim Huybrechts came out on top in the battle of the Belgian brothers as he and Ronny made history at the PDC World Championship at Alexandra Palace.
Siblings had never previously met at this event, and it was Kim - the younger by 20 years at 28 - who went through after a tense 3-1 victory, repeating his win from the Grand Slam of Darts in November.
Ronny took the first set 3-1 after a 13-dart finish and then went on to take a 2-0 lead in the second, but the match turned around.
Kim moved into a 2-0 fourth-set lead and a 110 checkout, finishing on double 16, saw him take the win.
He told Sky Sports 1: "That was the most toughest game I have ever played in my life.
"Ronny was by far the better player - I got lucky but I don't feel good. I was really nervous, I don't think I have ever been this nervous. I can promise the next round will be 10 times better."
Ricky Evans outplayed Ronnie Baxter to send the 19th seed spiralling out as a 3-0 loser.
The third set went to a deciding leg and 23-year-old Evans made use of the advantage of throwing first as he hit a fourth 180, followed by an accurate attempt at double six to claim victory.
Evans told pdc.tv: "I didn't feel many nerves tonight and I think experiences at the O2 and the Grand Slam earlier this year were a huge benefit to me.
"Winning on the Youth Tour regularly has given me huge confidence. It's a great format and helps with the steep learning curve I'm going through right now."
South Africa's Devon Petersen secured a spot in the first round of the with a 4-1 win over Malaysian qualifier Mohammed Latif Sapup.