The top four seeds in the WNBA playoffs advanced to the semifinals and one matchup will feature a record seven No. 1 draft picks on the court. The No. 1-seeded Las Vegas Aces and No. 4 Seattle Storm swept to advance, while the No. 2 Chicago Sky and No. 3 Connecticut Sun had to win a Game 3 on the road. The larger storylines are still the same. Let's take a look at the semifinal matchups and all the details you need to know before tipoff of the two best-of-five series on Sunday.

When are the WNBA playoffs?

The WNBA playoffs tipped off on Aug. 17 and run through Sept. 20, at the latest. They are early this year so players can join their national teams for the FIBA World Cup in Sydney, Australia. USA Basketball announced the training camp roster last week.

The semifinals tip off on Sunday. The WNBA Finals begin on Sunday, Sept. 11.

What is the WNBA playoff format?

The new format does away with single-elimination games, first-round byes and reseeding in-between rounds.

Teams played a best-of-three series in the first round with the first two games at the higher seed and a Game 3, if necessary, at the lower seed. The Sky and Sun both won Games 3 on the road to advance. The semifinals and Finals will be best-of-five in a 2-2-1 format starting at the higher seed.

The first-round matchups are No. 1 seed vs. No. 8 seed and No. 4 seed vs. No. 5 on one side of the bracket. Winners play in the semifinals. The other is 2-vs.-7 and 3-vs.-6, with winners meeting in the other semifinal. The WNBA does not seed by conference but rather by overall record. All top four seeds advanced to the semifinals.

Who is playing in the WNBA playoffs?

Semifinals

No. 1 Las Vegas Aces (26-10) vs. No. 4 Seattle Storm (22-14)

No. 2 Chicago Sky (26-10) vs. No. 3 Connecticut Sun (25-11)

First-round results

No. 1 Aces (26-10) over No. 8 Phoenix Mercury (15-21), 2-0

No. 2 Sky (26-10) over No. 7 New York Liberty (16-20), 2-1

No. 3 Sun (25-11) over No. 6 Dallas Wings (18-18), 2-1

No. 4 Storm (22-14) over No. 5 Washington Mystics (22-14), 2-0

How to watch

Semifinals

Games 1, Sunday

Seattle at Las Vegas, 4 p.m. ET on ESPN

Connecticut at Chicago, 8 p.m. ET on ESPN2

Games 2, Wednesday

Connecticut at Chicago, 8 p.m. ET on ESPN2

Seattle at Las Vegas, 10 p.m. ET on ESPN2

Games 3, Sunday, Sept. 4

Chicago at Connecticut, 1 p.m. ET on ESPN2

Las Vegas at Seattle, 3 p.m. ET on ABC

Games 4, Tuesday, Sept. 6 (if necessary)

Chicago at Connecticut, TBD on ESPN2

Las Vegas at Seattle, TBD on ESPN2

Games 5, Thursday, Sept. 8 (if necessary)

Connecticut at Chicago, TBD on ESPN2

Seattle at Las Vegas, TBD on ESPN2

Who won the 2021 WNBA championship?

The Chicago Sky pulled off a historic run to win the 2021 title as the No. 6 seed in the playoffs. They defeated the No. 5 seed Phoenix Mercury in four games, winning it back home at Wintrust Arena where Mercury star Diana Taurasi reportedly broke a door.

Chicago became the first team in the league's 25-year history to win the title without being the No. 1 or No. 2 seed. The Sky and Mercury were the first teams seeded outside of the top three to reach the Finals since the playoff format changed in 2016.

The Storm won titles in 2018 and 2020. The Aces and Sun have never won a title.

Who is the betting favorite?

The No. 1 seed Aces are favored at BetMGM at -110 from +135 to start the postseason. The rest of the field, in order: Sky (+350 from +250 previously), Sun (+350 from +500) and Storm (+500, held).

Keys to the semifinal games

No. 1 Aces vs. No. 4 Storm

Season series: Aces, 3-1. Average winning margin: 9.5 points

Aces notes: The Aces could have forward and two-time Sixth Player of the Year Dearica Hamby (9.3 ppg, 7.1 rpg, 26.5 mpg) back at some point in this series. Hamby was ruled out for 2-4 weeks on Aug. 10 with a right knee bone contusion. By Game 1, it will be about 2 1/2 weeks.

Storm notes: Gabby Williams (7.5 ppg, 5 rpg, 3.1 apg, 1.5 spg, 25.6 mpg) sustained a concussion in Game 2 of the first round and her availability would appear to be up in the air for the semifinals. She is a key part of their third-ranked defense.

A collection of No. 1s: The series will feature seven No. 1 draft picks, a record in both the WNBA and NBA, per ESPN Stats and Information. The five top picks from 2015 to 2019 will be on the court.

• Sue Bird (UConn), Storm, 2002

• Tina Charles (UConn), Storm, 2010 (drafted by Connecticut)

• Jewell Loyd (Notre Dame), Storm, 2015

• Breanna Stewart (UConn), Storm, 2016

• Kelsey Plum (Washington), Aces, 2017

• A'ja Wilson (South Carolina), Aces, 2018

• Jackie Young (Notre Dame), Aces, 2019

The other three standard starters: Storm's Williams (UConn, No. 4 in 2018 by Sky), Aces' Hamby (Wake Forest, No. 6 in 2015) and Aces point guard Chelsea Gray (Duke, No. 11 in 2014 by Sun).

What to expect: The intensity of the regular season finale. And a lot of shooting from beyond the arc.

The Storm and Aces are the two best 3-point shooting teams in the league and are both averaging 36.1%. The Aces average 9.5 makes a game and the Storm 9.3. They're also the best at the free-throw line, though the Aces get there an average 19 times a game and the Storm 15 — an aspect to watch in what will likely be a close game.

Wilson has been every bit an MVP candidate in leading the Aces. She averaged 22.8 points, 11.8 rebounds and was 52.9% from the field in their four games. In the first outing, she blocked five Storm shots. Stewart was similarly MVP caliber, averaging 22.8 points, 10 rebounds and 2.3 assists. She was 43.1% from the field and 10-of-22 (45.5%) from 3-point range.

Loyd will be an X-factor for the Storm. She scored 38 in the finale and came alive late to take Game 1 against the Mystics. Much like the other series, it will rely heavily on who gets the most stops. The Storm have the better defense, particularly when it comes to defending at the arc (32% opponent 3s). The X-factor for the Aces will be if they can play solid defense for a full 40 minutes against a team that has a lot of drive for a title in Bird's final season and Charles' longtime quest.

The Aces have signed their core to long-term contracts. The Storm are bound to look very different after free agency.

No. 2 Sky vs. No. 3 Sun

Season series: Sky, 4-0. Won by margins of four, eight, three and three points

Sky notes: Chicago is aiming for the league's first back-to-back championships since the Los Angeles Sparks in 2001-02, and the second in franchise history. General manager and head coach James Wade was named the WNBA Executive of the Year on Monday then signed a contract extension through 2025 on Wednesday.

Sun notes: Connecticut made the semifinals for the fourth straight season, but have yet to win a WNBA title. Only Bria Hartley and Jasmine Thomas, who are both out for the season with ACL injuries, did not play in the deciding Game 3.

What to expect: It is the third consecutive season the two have met in the postseason and the second it has been in the semifinals. The Sky, seeded sixth, upset the No. 1 seed Sun en route to their title last fall.

"We still have a bitter taste in our mouth from last season," Alyssa Thomas, known as the Sun's engine, told reporters after the win on Wednesday. Thomas is one of only three players in league history to average at least 12 points, six rebounds and six assists over a single season, per Across the Timeline.

The Sun are 2-9 against the Sky the last two years, but any stat can be cherry-picked to make a point (though winning is clearly the end-all, be-all here). The margins were close this season, and last season the Sky put up wins of six and 10 in the regular season and six, three and 10 in the postseason. The Sun won their games by 16 and 11.

There isn't much separating the two teams statistically. They offer the same offensive efficiency (105.8), are close in defensive efficiency (Sun 96.3, Sky 99.7) and have similar turnover percentages (Sun 19.3, Sky 18.1). The Sky are better at moving the ball around (21 assist ratio leads league; Sun 18.1). The Sun are better on the boards (55.7 rebound percentage leads league; Sky 50.8).

It will start and end with defense for the Sun, just as it got them out of the first round. The Sky were a league-best 48.1% from the field and bested that mark three of the four times against the Sun (50.8%, 59.3%, 42.9%, 56.9%). The first two games they were a combined 46% from 3-point range.

And a different player led the Sky in scoring each time out, a signifier of threats at every position. Jonquel Jones will be key in the paint for the Sun and the guards will have to hit some shots.