Hard to pronounce names

For a Japanese person, is it a bit hard to say names that end in ''sa'' with ''san''?

Ex: ''Masa-san,'' ''Tatsuhisa-san,'' ''Risa-san,'' etc.

Would it be too weird to call the person a nickname like ''Massan'' etc. instead?

For a Japanese person, is it a bit hard to say names that end in ''sa'' with ''san''?

No, it's not... at least not to me at all.

Would it be too weird to call the person a nickname like ''Massan'' etc. instead?

The idea of changing someone's name only because you cannot pronounce it is weird... it's like calling someone "Misternie" instead of "Mister Ernie" because the two "er" sounds in a row is difficult to pronounce :)

But you could ask that person if it's OK for you to call him/her that, because YOU personally find it difficult to pronounce it... but also depends on how close you are with that person and how regularly you are with that person...

The "sasa" sound is not hard to pronounce, and occurs naturally in some Japanese names (Sasaki, for example) and words.

However, the use of nicknames in conversation is quite common, and people don't really delve into the "why" of a nickname, so if someone found a particular name hard to pronounce with the honorific "san" for some reason (and that would be unusual, but this is all hypothetical), and they switched to some type of abbreviated form, no one would stop and think "Wait, why are they using that nickname? Is it because they found the actuall name hard to pronounce? How odd?"

More important would be if the relationship between the two people was such that use of a nickname was inappropriate, condescending, or rude. That would draw negative attention.

Note that sometimes nicknames are abbreviated forms like you suggested, and sometimes nicknames are inside jokes or even "codenames" to keep others in the dark about who is the subject of the conversation.

Thanks for answering, AK & DanH2009 :)

I also agree that it's important to think of whether or not using a nickname is appropriate given the relationship between people.
In my case, it would most likely be fine, but I'll ask my friend if he'd mind if I call him by a certain nickname.