Whitlock threw three 180s on his way to the third round, but his match against Perez went down to the fifth and final set - with the Australian having to fend off a difficult opponent.
One of three women who are competing in this year's World Championship, Ashton's tie against Meikle also went down to the fifth set, but she came up short against her fellow Briton.
Josh Rock has been touted as a future darts star and reinforced the hype with an impressive 3-1 debut World Championship win against Spaniard Jose Justicia.
Following his win, Rock was quick to back himself to go far in the competition.
"I'm confident I'll have a good run here," Rock claimed.
"That's the monkey off my back. It's hard to win your first game having never played on that stage before. It doesn't matter who you're playing, you need to play your game."
Elsewhere, world number 15 Dimitri Van den Bergh won in three sets against Phillipino player Lourence Ilagan, while Daryl Gurney lost by three sets to none against the lower-ranked Alan Soutar (rank 24 v rank 36).
