It almost seems at this year's Tal Memorial that leading the tournament is bad for your subsequent play. Alexander Morozevich led entering round 6 and lost, when he was caught by Vladimir Kramnik. Both promptly lost in this round, and were caught by Teimour Radjabov (who co-led after round 4, if I recall correctly), Fabiano Caruana and Magnus Carlsen. All five players are on +1 with two rounds to go, and lead Hikaru Nakamura by a scanty half-point margin.
Morozevich had Black against Evgeny Tomashevsky, and while Morozevich is the kind of player who presses with either color, the fact that it was against the tailender may have pushed him to go too far even by his own standards. Tomashevsky seemed amenable to a repetition before the time control, but Morozevich's 31...Ng7 indicated that he really wanted a decisive result. He got one alright, though it wasn't the one he wished for.
Kramnik, also a co-leader, also lost with Black against one of the "lesser lights". In his case, however, it wasn't "suicide" but an earned victory by Luke McShane that took almost seven hours to achieve. The play wasn't perfect, but matters came down to McShane's having the far more dangerous passed pawn and having far more play against Kramnik's king than Kramnik enjoyed against McShane's.
Had any one of Carlsen, Radjabov or Caruana won, that person would have enjoyed clear first. For Carlsen, it wasn't really a possibility. He was always defending against Hikaru Nakamura. The latter enjoyed a nagging pul in a Catalan, but it never turned into anything tangible. As for the other two, they played each other. Radjabov obtained a huge advantage straight out of the opening, but missed his best chance to win when he played 21.e6; 21.Rc7 puts Black at death's door. He missed that chance, and after another 42 moves of dour defense the young Italian pulled out the draw.
Finally, Levon Aronian had to work to save a draw as White against Alexander Grischuk, due to the latter's terrific preparation.
There are two rounds to go, and here's what we can look forward to in a few hours:
Round 8 Pairings: