This is the final event of the Grand Prix series, of which the top two finishers overall qualify for next year's Candidates tournament. Shakhriyar Mamedyarov and Alexander Grischuk lead thus far, but they have already played in their full complement of Grand Prix events. Teimour Radjabov is in third place overall, and Maxime Vachier-Lagrave is in fifth; they are playing, and with a good result either or both could leapfrog their way into qualification. (Ding Liren is in fourth overall, and is playing, but his qualification via the World Cup takes precedence, so that even if he wound up the overall winner of the Grand Prix the Candidates slots would go to the second- and third-place finishers.)
To guarantee himself qualification, Radjabov needs 98 and 4/7 points Grand Prix points from this last event (let's round up to 100), which he can achieve by finishing in clear first (170 points), clear second (140), clear third (110), or a two-way tie for third-fourth ([110 + 90]/2 = 100). Other combinations of ties for the top places would also work, but they're easy to figure out, so I won't bother to enumerate them. As for MVL, he's 128 and 4/7 points out of first, so he can only guarantee himself a spot by taking clear first, clear second, or tying for first and second. If Radjabov has a lousy event, then...I'm not entirely sure. MVL is 125 points behind Grischuk, and if he finishes in a two way tie for second-third he'd get 125 points on the dot. In that case it would come down to these tiebreaks, according to the Wikipedia page:
Let's hope it doesn't come down to #5, or really, to any of these criteria.
More info on the Wikipedia page, TWIC, and if you're desperate, the tournament site. Play starts tomorrow, at 9 a.m. ET/3 p.m. local time in Palma de Mallorca, Spain. That's where Bobby Fischer began his great run to the world championship in 1970, when he dominated the field in the Interzonal tournament, winning with a majestic score of 18.5/23. Will Palma de Mallorca 2017 mark a milestone for Teimour Radjabov or Maxime Vachier-Lagrave?