I think most had suspected Mantz would be running Chicago this fall, but Chicago has officially confirmed it in a press release. And Mantz has said specifically that he is targeting Khalid Khannouchi's 2:05:38 American record, which has stood since 2002.
Mantz ran 2:05:08 on Boston's non-record-eligible course in April.
“After Boston, where I finished with guys who have run 2:02 and 2:03, it doesn’t feel like a stretch to say I can run 2:05:30 on a looped, flat course.”