A friend is trying to pull the girl I like, what to do?

I know this girl whom I like, she has a lot of what I'm looking for, I'm friends with her but not besties or anything like that, but she's good friends with a close friend of mine. And I have this other friend, whom I met a couple of months ago but really started talking and getting on since a month ago. So this girl recently broke up with her boyfriend, and my friend also did the same with his girlfriend, just a day apart. 1 week ago. I didn't see him as a threat at all as he seemed interested in another friend I have, so I took him along to a study session. There he got the chance to meet properly and talk to both of my (girl) friends. Up to that point everything still good, but since Monday, he's been actively flirting with my girl (not as in possessive but rather as to not confuse you more). In lessons he keeps doing exactly what I would do, throwing some paper at her, playing footsie, annoying her with another classmate that no one likes, pretty much what my plan was. So I'm right now on my back foot, I know I could still get back into it, but I need ideas how, I don't want to be a copy cat, and I don't want to but I want to fight for her. How can I out flirt him? what should I do? how do I approach the situation, because she seems to be falling for it. Any other suggestions??