The final day of the opening weekend of the Overwatch League's 2021 season finished with explosive matchups as the Houston Outlaws, Florida Mayhem and Toronto Defiant picked up wins on Sunday.

The biggest upset of the Western Region thus far was the first match of the day, with the Outlaws (2-0)taking out the reigning world champion San Francisco Shock (1-1) 3-2 in six games.

Houston started strong on Lijiang Tower with a 2-0 win, powered by the first-year tank duo of Myung-heum "JJANGGU" Cho and Min-jun "PIGGY" Shin. JJANGGU had a great outing on Reinhardt against one of the best Reinhardt players in the league in the Shock's Matthew "super" DeLisi, while PIGGY played exceptionally well on D.va and Zarya throughout the series.

After Houston and San Francisco split Game 2 on Blizzard World 3-3, the Outlaws dominated Game 3 on Dorado, full-holding the map for a 1-0 win. This map featured fan-favorite player-coach Jacob "JAKE" Lyons making his return to league play on Brigitte. With their backs to the wall, the Shock buckled down and got to work, grinding out a 4-3 win on Temple of Anubis in Game 4.

From there, the Shock went into their bag and pulled out creative plays to take Game 5 on Oasis 2-0 and force a tiebreaker Game 6 on Havana. The Shock's defense was solid, not allowing the Outlaws to complete the first point, but Houston held stronger, led by a timely clutch Earthshatter from JJANGU and a standout performance from DPS Jung-woo "Happy" Lee, who played well all series. Houston took the final map 1-0 to hold off the reverse sweep and pick up a massive win that should send shockwaves through the OWL landscape.

Sunday's other intense matchup saw the Defiant (2-0) come back from an 0-2 deficit to reverse sweep the winless Atlanta Reign 3-2. This entire series boiled down to each team's preferred team composition clashing, with the Reign favoring Reinhardt brawl and the Defiant running "Double Bubble" Winston-led dive compositions.

Atlanta struck first with a dominant display in Game 1, taking Nepal 2-0. The Reign continued to surge into Game 2 on Blizzard World, winning the map 3-2 with some clutch teamfighting and some timely spawn-camping. At this point, it looked like the Defiant wouldn't be able to turn the corner and find a spark to beat the Reign, but Toronto recovered well in Game 3.

The Defiant started to come into their own in Game 3, winning Dorado on the back of support and eventual player-of-the-match Jung-won "Lastro" Mun. With Lastro's Ana landing big Biotic Grenades and Sleep Darts, Toronto pushed back against Atlanta's aggressive frontline, who were routinely getting blown up at this point.

After taking Temple of Anubis 2-1 in Game 4, it all came down to Game 5 on Busan. There, the Defiant continued to surge with precise dives leading to a clean 2-0 win to secure the reverse sweep. With the win, the Defiant look to continue to build momentum into the May Melee as a potential darkhorse candidate to make a deep playoff run.

In Sunday's other game, the Mayhem improved to 2-0 after taking down the 0-2 Vancouver Titans 3-1. The Mayhem didn't do anything particularly incredible to beat Vancouver, a team of mostly rookies and journeymen and lacking in star power. Florida started by taking Nepal 2-1 in Game 1, then took King's Row 3-2 to go up 2-0 in the series at the break. After halftime, the Titans got on the board in Game 3 with a 2-1 win on Havana, but the Mayhem turned things around in Game 4 on Volskaya Industries with a 2-1 triumph to secure the series.

Week 2 of the Overwatch League kicks off on Friday with two matches:

Paris Eternal vs. Vancouver Titans

Los Angeles Gladiators vs. London Spitfire

Overwatch League standings, with win-loss record and map differential:

T1. Philadelphia Fusion (East), 2-0, 5

T1. Chengdu Hunters (East), 2-0, 5

3. Florida Mayhem (West), 2-0, 4

4. Toronto Defiant (West), 2-0, 3

5. Houston Outlaws (West), 2-0, 2

T6. Dallas Fuel (West), 1-1, 1

T6. Seoul Dynasty (East), 1-1, 1

T6. San Francisco Shock (West), 1-1, 1

9. Shanghai Dragons (East), 1-1, even

T10. Boston Uprising (West), 0-0, even

T10. Paris Eternal (West), 0-0, even

T10. New York Excelsior (East), 0-0, even

T10. London Spitfire (West), 0-0, even

T10. Hangzhou Spark (East), 0-0, even

T10. Washington Justice (West), 0-0, even

16. Atlanta Reign (West), 0-2, -3

T17. Vancouver Titans (West), 0-2, -4

T17. Los Angeles Gladiators (West), 0-2, -4

19. Los Angeles Valiant (East), 0-2, -5

20. Guangzhou Charge (East), 0-2, -6