1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. g1f3  3... d7d5  4. g2g3  4... f8b4 One of the plausible ways to meet the Catalan. There is a very long list of strong GMs who have it in their repertoires. 5. b1d2 This move is a favorite of Dubov. White sacrifices a pawn in return for a strong center. 5... d5c4  6. f1g2  6... b7b5  7. a2a3  7... b4e7  8. f3e5  8... f6d5  9. a3a4 But this might not be the most accurate. 9... c7c6  10. e1g1  10... a7a5 Alekseenko keeps his king in the center for the time being. 11. e2e4  11... d5f6 The knight is destined to defend the kingside. 12. e5g4 Until traded. 12... f6g4  13. d1g4  13... h7h5 This is what Alekseenko was waiting for! 14. g4e2  14... e6e5 Instead of taking a pawn, Black offers one! 15. d4e5 After a lengthy thought, Tabatabaei decided that he can open files like that too. 15... b8a6  16. e5e6 But White does not want to keep the pawn at all, he needs the open files! 16... c8e6  17. e4e5 Still, Tabatabaei underestimated Black's next move. 17... a6b4 A powerful exchange sacrifice!