An interesting chess puzzle ;)

Originally posted by schakuhr
1. Bg5 b3?!
2. Rd2+! (2. f7? b2+ =) Ka1
3. f7 and f8Q wins.

Better for black seems
1. Bg5 Rg8
2. Rd2+! (don't know if white wins after 2. f7!? Rc8+) Kb3
(2. ...Ka1 loses to 3. f7 Rf8? 4. Bf6# and Ka3 also isn't good: 3. f7 Rf8 4. Rf2 b3? 5. Be7🙄

3. f7 Rf8
4. Rf2 a3
5. Bh6 a2
6. Rf3+! Ka4/c4
7. Kb2 wins.

Well the real challenge here is after 1.Bg5 b3!? 2.Rd2+ Ka1 3.f7! Rxg5 4.f8Q Rg1+ 5.Rd1 Rg2! 6.Qa3+ Ra2 7.Qc5 Rh2! and it seems like Black has a positional draw (8.Rd2 Rh1+ 9.Rd1 Rh2 10.Qa3+ Ra2 11.Qxa2 Kxa2 12.Rd2+ Ka1=) but it is not so. Can you find why?