In contrast to the hostile reception for Littler, Dutch duo Van Veen and Michael van Gerwen were roared on to the stage by the fans in Rotterdam.
However, the pair were unable to deliver in front of their home crowd with Van Veen out of sorts against a much-improved Humphries as the Englishman claimed a comfortable 6-2 win.
That took the defending champion above Van Veen into fifth and to within three points of Van Gerwen in the final play-off place.
Van Gerwen had the chance to extend that gap to five but he was swept aside by Clayton, a 6-2 triumph for the Welshman leaving the Dutch fans stunned and keeping the race for the top four in the balance.
Had Humphries completed his comeback against Littler in the semis, it could have been even tighter.
Stephen Bunting still has hope of qualifying despite a 6-1 loss to Rock, in which he found himself 4-0 down despite averaging 114 as a result of the Northern Irishman starting with four from four on the doubles.
Price stays third despite a second quarter-final exit in as many weeks.
