Bestow Curse and concentration

I'm wondering the ruiling on Bestow Curse and concentration.

Let's say my cleric already has "Bless" active and concentrating on that. 

Then he casts "Bestow Curse" with a level 3 spellslot on an enemy, but the enemy SAVES against the spell...

Does he still keep his concentration on "Bless"?

Casting a concentration spell immediately ends any already active concentration spell. From sage advice compendium

If I’m concentrating on a spell and I cast another spell that requires concentration, when does my concentration on the first spell end?

If you’re concentrating on a spell, your concentration on it ends immediately when you start casting another spell that requires concentration.

 Thank you! That was a fast answer!