Just limiting the discussion to the games of 2700s for now, there were three games out of the 14 involving 2700-rated players at the Qatar Masters where the favorite failed to win. Second seed Vladimir Kramnik drew with Stelios Halkias, who had the chutzpah to play the Evans Gambit against him! He didn't get anything out of the opening, but in the middlegame was making progress and managed to win a pawn. In the ending, however, he let his advantage slip, and finally decided to repeat rather than try to grind anything out.
The biggest full-point upset came on board 7, where Baadur Jobava lost with White against his countrywoman Bela Khotenashvili. His 16.Bxd5 looked a bit crazy to me (a viewpoint confirmed to me by a grandmaster friend) and his considerably lower-rated opponent (though still a GM) outplayed him convincingly and impressively.
Finally, the third upset was remarkable and flashy. As with Jobava, Arkadij Naiditsch lost with the white pieces, to Indian GM R. Rajpara Ankit. Naiditsch had the better of play in the early going, but was gobsmacked by the fantastic sequence 19...Bh4 (intending 20...Bg3) 20.Kg2 (stopping ...Bg3) Bg3!! anyway! In fact 20...Bg3 may not have been the best move due to 21.Nf6+! followed by 22.Qxd8+ and 23.Kxg3, when White stands better, but Naiditsch either missed this or thought that his approach of taking the "free" bishop was even better. It wasn't, and Ankit won a spectacular game.
These three games (sans notes) can be replayed here.