World champion Viswanathan Anand maintained his slender half-point lead after playing an eventful draw with former World champion Veselin Topalov of Bulgaria in the sixth round of the Morelia-Linares chess tournament.

Anand took his tally to four points out of a possible six after the end of the penultimate round of the event here and is likely to play the second half at Linares as a leader when it begins in the Spanish hamlet on February 29. In the final round at Morelia, Anand meets Vassily Ivanchuk of Ukraine.

With eight rounds still to come, Aronian remained in sole second spot on 3.5 points while Radjabov eclipsed Carlsen from the joint third spot to share it now with Shirov and Topalov on three points each.

Results (Round 6): Veselin Topalov (Bul, 3) drew Viswanathan Anand (Ind, 4); Levon Aronian (Arm, 3.5) drew Peter Leko (Hun, 2.5); Vassily Ivanchuk (Ukr, 2.5) drew Alexei Shirov (Esp, 3); Teimour Radjabov (Aze, 3) bt Magnus Carlsen (Nor, 2.5).