jabird - there are some coach services that run up to Trieste from Croatia - I think Zagreb, Rijeka, Porec, Pula and Split are all served. There's also a small coastal ferry that runs from Rovinj and Porec up to Trieste - a fun way to travel - but it might be summer only. Frequencies are fairly limited on the coaches though so you may have to overnight in Trieste - a great city to spend time in though!