2018 ITTF Challenge Series
The 2018 ITTF Challenge Series was the second season of the International Table Tennis Federation's secondary professional table tennis tour , a level below the ITTF World Tour . 
<triplet> 2018 ITTF Challenge Series <subj> table tennis <obj> sport <triplet> International Table Tennis Federation <subj> table tennis <obj> sport <triplet> ITTF World Tour <subj> International Table Tennis Federation <obj> organizer <subj> table tennis <obj> sport