Sebastan,
You can configure an access-list for the source and destination and then do an IP Packet Detail Debug on the ACL.
For example:
access-list 100 permit ip host 10.1.1.1 host 10.2.2.1
deb ip packet 100 detail
Also, watch out for the CPU spike when you run debugs. Running Debug IP Packet detail without an ACL can melt down the router based upon the traffic at that time. So, it is highly recommended that you configure an ACL and be specific as possible and then run the debug against the ACL.
I hope it helps.
Regards,
Arul