Natus Vincere and G2 Esports swept their semifinal opponents Sunday to reach the upper-bracket final of Group A at the Intel Extreme Masters event in Katowice, Poland.

Also on Sunday, IHC Esports and Team Spirit stayed alive in the competition by winning in the Group A lower-bracket quarterfinals, and Heroic and Fnatic won their opening matches in Group B's upper bracket.

The $1 million Counter-Strike: Global Offensive tournament began Wednesday with the 16-team, double-elimination play-in stage to determine the final eight spots in the group stage. First-round play-in matches consisted of a single map, while all other play-in matches were best-of-three.

The four teams that advanced on Wednesday -- BIG, OG, Ninjas in Pyjamas and Cloud9 -- joined the eight teams that were already seeded into the group stage: Team Liquid, Natus Vincere, G2 Esports, FaZe Clan, Heroic, MOUZ, Team Vitality and Outsiders.

Group play will run from Saturday through Tuesday, with two eight-team groups competing in a double-elimination format of best-of-three matches. The two group winners advance to the semifinals of the single-elimination playoffs. The two group runners-up go the playoff quarterfinals as high seeds, and the third-place teams from each group head to the playoff quarterfinals as low seeds.

The best-of-three quarterfinals are scheduled for Feb. 10, and the best-of-three semifinals are set for Feb. 11. The winner of the best-of-five grand final on Feb. 12 will earn $400,000 and a berth in the $1 million IEM Cologne event scheduled for July 25-Aug. 6 in Germany.

On Sunday, Natus Vincere blew past Team Liquid 16-5 on Inferno before notching a 19-17 overtime win on Anubis for the 2-0 sweep. Russia's Denis "electroNic" Sharipov had a game-high 45 kills for NaVi and Ukraine's Oleksandr "s1mple" Kostyliev added 43 kills on a plus-14 kills-to-deaths differential.

G2 bested FaZe Clan 2-0, winning 16-14 on Nuke and 16-7 on Ancient. Leading G2 with 47 kills apiece were Justin "jks" Savage of Australia (plus-21 K-D) and Nemanja "huNter-" Kovac of Bosnia and Herzegovina (plus-13).

Liquid and FaZe were not eliminated just yet, instead dropping into the lower-bracket semifinals.

To open the Group A lower bracket, IHC Esports narrowly got past Cloud9 2-0, winning 16-14 on both Inferno and Mirage. Garidmagnai "bLitz" Byambasuren of Mongolia carried IHC with 47 kills and a plus-11.

Team Spirit rallied past BIG 2-1. After losing the opening map 16-10 on Nuke, Spirit won 16-11 on Mirage and clinched it by prevailing 16-10 on Anubis. Igor "w0nderful" Zhdanov of Ukraine racked up 70 kills and a plus-29 K-D.

Heroic kicked off its journey in Group B by beating Complexity 2-1. They sandwiched a 16-13 loss on Vertigo with wins of 16-11 on Inferno and 16-8 on Overpass. Jakob "jabbi" Nygaard led the all-Danish Heroic roster with 70 kills and a plus-18.

Likewise, Fnatic beat Outsiders 2-1. After opening with a 16-12 victory on Vertigo and falling 16-8 on Mirage, Fnatic used overtime to earn the decisive win, 19-16 on Overpass. William "mezii" Merriman of Great Britain guided Fnatic with 63 kills on a plus-9.

The event continues Monday with six more matches:

--FaZe Clan vs. IHC Esports (Group A lower-bracket semifinal)

--Team Liquid vs. Team Spirit (Group A lower-bracket semifinal)

--Heroic vs. OG (Group B upper-bracket semifinal)

--Team Vitality vs. Fnatic (Group B upper-bracket semifinal)

--Complexity vs. MOUZ (Group B lower-bracket quarterfinal)

--Ninjas in Pyjamas vs. Outsiders (Group B lower-bracket quarterfinal)

Intel Extreme Masters Katowice prize pool

1. $400,000, berth in IEM Cologne

2. $180,000

3-4. $80,000

5-6. $40,000

7-8. $24,000

9-12. $16,000

13-16. $10,000 -- Cloud9, BIG, TBD, TBD

17-20. $4,500 -- ENCE, Sprout, MIBR, FURIA Esports

21-24. $2,500 -- Permitta Esports, Evil Geniuses, Grayhound Gaming, paiN Gaming

--Field Level Media