Derek Fisher Photo: Matt Barnes Is Gonna Hate This ...

Here's Derek Fisher posing with his girlfriend Gloria Govan -- on their way to an international birthday celebration together.

So, Matt Barnes is gonna hate this, right?

You remember ... Barnes hates Fisher's guts -- because they used to be friends and Matt feels he violated the bro code by dating his baby mama. In fact, they fought over it last year and Matt has still vowed to beat up Fisher when they cross paths in the future.

Which brings us to this pic, which Gloria posted -- and then almost immediately removed from her Instagram.

Our good friends at BSO captured the shot ... and believe Glo removed it because she knows the pic will piss off Barnes and start a brand new round of beef.