Result for Quarter final here.
Mamedyarov keep his no tie break record clean as he was eliminated 1.5-0.5 by Karjakin. In their game 2, Mame with white considered only one tiny chance to equalized, but the game went to an opposite bishop endgame with rook then dully drawn.
Svidler resign the first game to Malakhov after the later underpromoted a pawn into Knight to give a nice check. White then forced into mate and quickly resign. After this Svidler try a KID as black but Malakhov maintained good equality and Svidler quickly declared a draw.
The two tie breaker, first is Ponomariov who fast enough to give Gashimov time trouble in all games. In rapid 1, Gashimov quite winning but blundered a lot in time trouble, rapid two he burned a lot of time and lost badly (=blundered a rook). Rapid 3 after an uncommon opening Gashimov again powerless to win the game and admit a draw.
Jakovenko also clueless to Gelfand, the White. Both play a draw in rapid 1, but Gelfand turn the table in rapid 2 and 3.
So the semi final pairing are :
Boris Gelfand - Sergey Karjakin
Gelfand born in 1968 his GM title was earned in 1989 while at that time Karjakin still one year to go before come out of this world. Meanwhile Karjakin is a "fast" one by 2002 already called a GM, he is also fast in other thing like get married in age 19 (2009, wikipedia), not sure how old Gelfand on this. Conclusion, age different not much give a pattern. Although in other sport this age different is like Maradona vs Ronaldinho , or Liem Swei King vs Taufik Hidayat (ok, they are Badminton player).
They are regular customer to each other, the previous meeting is compiled here:
1. Karjakin vs Gelfand ½-½ 26 2004 Pamplona Tournament C42 Petrov Defense
2. Gelfand vs Karjakin ½-½ 22 2006 Corus Wijk aan Zee E05 Catalan, Open, Classical line
3. Gelfand vs Karjakin ½-½ 26 2008 FIDE Grand Prix E34 Nimzo-Indian, Classical, Noa Variation
4. Gelfand vs Karjakin 0-1 46 2008 Amber Tournament (Blindfold) A07 King's Indian Attack
5. Karjakin vs Gelfand ½-½ 46 2008 Amber Tournament (Rapid) C24 Bishop's Opening
6. Karjakin vs Gelfand ½-½ 89 2008 Tal Memorial Blitz E10 Queen's Pawn Game
7. Gelfand vs Karjakin ½-½ 53 2008 Tal Memorial Blitz A28 English
8. Karjakin vs Gelfand 1-0 37 2009 World Blitz Championship C10 French
9. Gelfand vs Karjakin 1-0 47 2009 World Blitz Championship A37 English, Symmetrical
10. Karjakin vs Gelfand ½-½ 36 2009 FIDE Jermuk Grand Prix C43 Petrov, Modern Attack
11. Gelfand vs Karjakin 1-0 45 2009 4th FIDE Grand Prix D15 Queen's Gambit Declined Slav
Gelfand is playing safe strategy with no hesitation to have a draw when playing in not familiar position. Meanwhile Karjakin is one extra day for preparation and Gelfand already in marathon for few days.
Ruslan Ponomariov - Vladimir Malakhov
Lesser story to be told here. Malakhov is hardly a popular chess player before. He played in Candidate Match Mexico 2007, played in World Cup 2005 against Carlsen. U14 Champion in 1993. After his pairing with Wesley So he was blessed as one of popular chess player now. He is working daily as a scientist. Played a Slav defence.
Ponomariov is a former winner of this knock out tournament, so he has the experience. Played fast in rapid as shown in his match to Gashimov. His record of meeting Malakhov has only once, Ponomariov vs V Malakhov ½-½ 2009 LIII Campeonato D15 Slav. At least, Pono will be aware of his opponent familiar opening and not fall to Malakhov's preparation, which is quite lethal, plus Malakhov got one day extra to do it.