Two Robert Simpson penalties to one by Ally Stevenson saw Dalziel 6-3 ahead at the break but it was lock Andy Hill's interception and eighty yard burst for the only try of the game which clinched it for Dalziel.
Stevenson slotted an injury time penalty for Whitecraigs to snatch a losing bonus but Dalziel now have to be odds on to take the National 1 title.