Airlines of India - 9W connecting to US in YYZ

I have a flight BRU-YYZ with Jet Airways connecting to an American Airlines flight to ORD. So changing from T1 to T3.
Can I stay in transit or do I have to clear canadian immigration and customs before entering US ?

You cannot stay in transit as YYZ as the terminals are not linked. Clear Canadian Customs and Immigration formalities at T-1, proceed to T-3 with your bags for US Customs and Immigration pre-clearance. If AA has an interline agreement with 9W, possibly your bags could be transferred for pick up and clearance at T-3.

Thanks for your advice. Will travel on Saturday.