How can rsync with ssh be used on a non standard ssh port

[eculp at casasponti.net]

Test example.

I need to sync a directory from my machine to another that is using  
port 722 rather than 22.  I can use ssh -pm722, scp -P 722 fine but I  
prefer rsync for the backup due to configuration flexibility.  The man  
says:

rsync [OPTION...] SRC... rsync://[USER@]HOST[:PORT]/DEST

Which I translate to something like:

rsync -avz /almacen/testDir rsync://backupMachine.com:722/backup/

but I get the following:

rsync: server sent "SSH-2.0-OpenSSH_5.1p1 FreeBSD-20080901" rather  
than greeting
rsync error: error starting client-server protocol (code 5) at  
main.c(1504) [sender=3.0.4]

I've tried variants to the point of no return.  Help would be appreciated.

Thanks,

ed