次于

second after / second only to

next in sequence / second / the second (day, time etc) / secondary / vice- / sub- / infra- / inferior quality / substandard / order / sequence / hypo- (chemistry) / classifier for enumerated events: time

to go / to take / sentence-final interrogative particle / variant of 於|于[yu2]

(of time or place) in; at; on / (indicating any indirect relation) to; toward; vis-à-vis; with regard to; for / (indicating a source) from; out of / (used in comparison) than / (used in the passive voice) by

second only to ...; ranking behind only ...