The two teams involved in one of the biggest trades of the WNBA off-season had their first on-court meeting Wednesday morning.

Chalk one up in favor of the Washington Mystics.

Led by former Chicago Sky star Elena Delle Donne, the Mystics marched into Allstate Arena on “Field Trip Day” and earned an 82-67 win in front of 6,714 mostly school-aged kids.

“It definitely felt weird coming in here being in the guest locker room, being on the other bench,” said Delle Donne, who scored a game-high 21 points. “But my teammates were great. Even in the locker room, they were like, ‘How are you feeling?’ ”

Delle Donne said she was a little nervous, but it rarely showed. She was her usual smooth self and didn’t force anything while connecting on 7 of 15 field goals.

In 2013, the Sky made Delle Donne the No. 2 player taken in the WNBA draft, behind Brittney Griner.

Delle Donne guided the Sky to its first playoff appearance in history that summer, and then to the WNBA Finals in 2014.

But Delle Donne demanded to be traded this off-season, citing a desire to be closer to her family and special-needs sister in Delaware.

So the Sky and Mystics, who seesawed back-and-forth in the first half before the Mystics pulled away late in the second half, worked out a trade that sent Delle Donne to Washington, and Stefanie Dolson and Kahleah Copper to Chicago.

The Sky also got the No. 2 pick in the 2017 draft, which it used on South Carolina center Alaina Coates, who has yet to play because she is recovering from ankle surgery this winter.

Dolson had 13 points and 11 rebounds for the Sky. She has put together back-to-back double-figure scoring games after getting 23 points at Atlanta on Sunday, the only win of the season so far for the Sky (1-3).

“We executed pretty well and we competed hard,” Dolson said. “We gave up, me personally, too many offensive rebounds, and I’m really disappointed with myself.

“We just need to get back on the court, re-evaluate and get ready for Friday (when the Sky faces the Mystics in Washington).”

Dolson was one of four double-figure scorers for the Sky. Chicago native and point guard Cappie Pondexter led with 17 points while forward Tamera Young had 14 points and former DePaul star Allie Quigley had 13 points, including 3 three-pointers.

It was Quigley’s first game back for the Sky. She was late to report for the season because her off-season team in Turkey advanced to the league championship series.

Her club lost to a team led by Sky point guard Courtney Vandersloot, who watched the Sky-Mystics game in street clothes and likely will play Friday.

With a new coach in Amber Stocks, new players and some veteran who are just returning, it’s uncertain when the Sky will hit on all cylinders.

“That’s the crystal ball that we all want to know,” Stocks said. “Basketball is a game in which you have to expect the unexpected and it’s a game of adjustments.”

Washington (2-2) also got double figures from four players.

Tierra Ruffin-Pratt scored 15 points, while Tianna Hawkins and Ivory Latta scored 12 and 10 points off the bench respectively.