Here is what I got: <div id="list"> <ol> <li>Ordered list 1</li> <li>Ordered list 2</li> <ul><li>Unordered list inside ol ul</li></ul> <ol><li>Ordered list inside ol ol</li></ol> <ol> <ul> <li>Unordered list</li> <ol><li>Ordered list inside ul</li></ol> <ul> <ol> <li>Ordered list 1</li> <ol><li>Ordered list inside ol ol</li></ol> <ol> </div> I need somehow replace LI tags only inside div id="list" - OL tags I need so that it replaces only LI tags only within the first OL tags and not UL or the once inside OL - OL tags I tried using preg_replace_callback but it only replaces all LI tags inside id="list" and from what i figured it will be over my head to limit replacement only with first ol tags and not the rest, so I been suggested to try out PHP DOM since it should be as easy as div id="list" - OL I would appreciate if someone got me started with the code, maybe with something as replacing all LI tags with in the first OL tag within the whole content.