Sunderland's Beth Mead hit a hat-trick two days after a car crash to inflict a first defeat of the season on Women's Super League 1 leaders Chelsea.
Mead, who rolled her car three times as she avoided a deer, opened the scoring after the break, twice finding herself free to beat goalkeeper Hedwig Lindahl.
The 20-year-old completed her treble 18 minutes from time, heading in at the back post following a corner.
Abbey Holmes's long-range effort helped Sunderland move to second in the table.
Chelsea's Ji So Yun had the visitors' best chances of the game but her direct free-kick and close-range effort failed to really trouble Sunderland goalkeeper Hilde Gunn Olsen.
Sunderland, who were promoted from the second tier last season, earned their best result of the season against last season's runners-up and are now just two points behind Chelsea.
Mead's hat-trick takes her tally to eight for the season, making her WSL 1's top goal scorer.
Chelsea Ladies assistant manager Paul Green: "We've got to congratulate Sunderland on a very profession performance, they deserved the victory and Beth Mead took her goals very well.
"It's just a little reminder that you can't drop your standards at this level. I think we were a little bit below par and Sunderland capitalised on that."
Sunderland Ladies forward Beth Mead: "I'm lost for words, the girls were outstanding today.
"I was over the moon to get the goals, I missed a few last week but I had my chances today and I took them.
"We belong in this league and we're showing people now why we do. People look at us as an average team and I think we've shown today that we are one of the best at the moment."
Sunderland Ladies: Olsen, Holmes, Bannon (c), Greenwell, Furness, Chaplen (McFadden 72), Ramshaw (Kelly 85), Roche (Joice 72), Mead, McDougall, Williams.
Subs not used: Wilson, Sharp.
Chelsea Ladies: Lindahl, Blundell (Banusic 54), Bright (Spence 56), Flaherty, Fahey, Davison, C. Rafferty, Borges, Chapman (c), Ji, Aluko.
Subs not used: Hourihan, Kirby, Meiwald, L. Rafferty.
Referee: S. Hudson