The 15-year-old became one of the youngest players to win a match in a ranking event when he beat Lu Niang in the first round in Leicester.
But the teenager was unable to get the better of Lines - who he plays alongside at Northern Snooker Centre in Leeds - going down 11-2 in a low-scoring match.
Lines, almost a veteran aged 26, said: “It wasn’t nice for me. I know Stan really well because we play at the same club.
“He’s such a good kid. It was a nightmare draw – apart from my dad (fellow professional Peter Lines) he’s the one I didn’t want to play.
“It’s not enjoyable for either of us because we are friends so I didn’t want to be the one to put him out of the tournament.
“I played a decent frame – even though I only scored 11 points, I didn’t give him a good chance.”
Lines went on to beat former world champion Stuart Bingham, before falling in round four to Liang Wenbo, who earlier had knocked out another Leeds player, Sanderson Lam.