Shelby Lyman: On ChessWhen two ex-world champions play, the resultis not usually a slaughter.But such was the consequence of an encounter between Michael Tal and Tigran Petrosian in the last USSR team competitions.Tal racked up Tigran with textbook techniques; he developed his pieces, moved them to better squares, focused on the king, sacrificed till mate was inevitable.Petrosian, the perfect foil, personified dilatoriness: developing and un-developing a knight, “demaneuvering” his bishop and queen, exchanging with loss of tempo as the pressure of the white pieces mounted and then climaxed.Though this was the same Petrosian who had thrashed Tal a year before in a well-known game, here, so easy was Tal’s task that another ex-world champion, Dr. Max Euwe, remarked to me that Tal did not have to be himself to win. Petrosian ina display of self-immolation had spared the victor the usual preliminary exertions.The early end came on rapidly from the position given in Diagram One. Black has just moved his queen’s bishop from Q2 to Kl in order to free the knight, which was guarding the bishop, for its own development.BLACKPETROSIANdO NO 90 Oax NX dXr*\ NQR QN QB QKB KN KRTALWHITEWhite wins I How?CollisionUnfortunately, sealed the blackB-Klkingwhite’s N( K4)-N5position. Whereupon Tal sacrificed a knight for an unstoppable classic mate threat.What’s mo ve ? check of course!After black’s1 . . PxN; and 2. NxPcheck, K-Nl; 3. Q-B4!, the threat 4. Q-QR4 is un-meetable. (See Diagram Two)BLACKPETROSIANdO NO 90 O X 9X NX dX8765n □□p'ny s'nr ^ * ^□miie321■mmv MB 's9\w\w\\\w\\\8QR QN QB Q K KB KN KRTALWHITEQ-R4 beckons\Petrosian’s try 3 . . N-Q2 (see Diagram Three) was met head-on with 4. RxN! (He had hoped to answer 4. Q-R4 with . . N-B3, whichwould stop the threatened mate.)BLACKPETROSIANdO NO 90 O X 9X NX dXQR QN QB QKB KN KRTALWHITENo dice!Now there was no meaningful choice. The move 4 . . QxR wouldhave yielded checkmate after 5. Q-R4 etc., whereas4 . . BxR (which wasplayed) triggered 5. BxP check and a black resignation.Black, understandably, had no heart for the rest of the charade, i.e.,5 . . RxB; 6. QxR check,K-Rl; 7. QxP, K-Nl; 8. R-K7 (see Diagram Four) and mate next move.Has Petrosian ever before lost so pitifully ?BLACK , PETROSIANdO NO 90 O9X NX dX□□□□QR QN QB QKB KN KRTALWHITEFinisThe move-by-move recordof the game follows:TalPetrosian(white)(Black)1. P-K4P-KN32. P-Q4B-N23. N-QB3P-Q34. N-B3N-KB35. B-K20-06. 0-0N-B37. P-Q5N-Nl8. R-KlP-K49. PxP e.p.BxP10. B-KB4P-KR311. N-Q4B-Q212. Q-Q2K-R213. P-K5PxP14. BxPN-K5?!15. NxNBxB16. N-KB3B-N217. QR-Q1Q-Bl18. B-B4B-Kl19. N(4)-N5 checkPxN20. NxP checkK-Nl21. Q-B4N-Q222. PxNBxR23. BxP checkResigns./.•/.v.v/.vc