Four-time Wimbledon champion Serena says tournament organizers "like to put us on Court 2 — me and Venus — for whatever reason."
She adds: "Maybe one day, we'll figure it out."
The defending champion won her second-round match on Court 2 Thursday. Five-time champion Venus won there Monday.
Tournament spokesman Johnny Perkins says there's no intentional snub.
Says Serena: "Yeah, they're never moved across."
The Williams sisters have combined to win nine of the last 11 Wimbledon singles titles.