Crystal Palace deservedly claimed a first Premier League win of the season with a 2-1 victory over champions Chelsea at Selhurst Park.
Palace received a stroke of luck in scoring their first league goal in five months, ending a drought of 731 minutes stretching back to last season.
The scruffy strike was recorded as a Cesar Azpilicueta own goal, but Palace had one of their own when the excellent Wilfried Zaha struck before half-time as Palace won for the first time this season at the eighth attempt.
Chelsea, who had equalised through Tiemoue Bakayoko, had been seeking to respond from the loss to Manchester City ahead of Wednesday's Champions League clash with Roma.
They are now nine points behind leaders City after a poor performance. Palace, who won at Chelsea in April, had not scored a league goal since Patrick van Aanholt's last-minute strike in the 4-0 win over Hull on May 14.
Their dismal start to the season was expected to continue against the champions, but the return of Zaha from injury galvanised his teammates.
Townsend early on found Zaha, who turned away from Azpilicueta before seeing his shot saved by Thibaut Courtois.
The only surprise when Palace scored was that Zaha was not a central protagonist. Townsend snuck in behind Marcos Alonso and pulled the ball back for Yohan Cabaye.
His attempt to control the ball was interrupted by Luiz, it ricocheted back off the Frenchman and wrong-footed Courtois by deflecting off Azpilicueta. The joy and relief was soon followed by wit. "We're Crystal Palace, we score when we want," sang home supporters. The celebrations were short lived.
A Cesc Fabregas corner was met by Bakayoko, who lost his marker and headed the ball into the ground and the net for his first Premier League goal.
Palace, and Zaha, would not roll over. Zaha ran at Chelsea and his shot deflected wide.
The Blues had another good chance when Michy Batshuayi - given an opportunity with Alvaro Morata kept in reserve for Roma due to his fragile hamstring -- headed over a corner from Fabregas, who later fired a free kick narrowly over. The visitors were left to rue the miss when Mamadou Sakho epitomised the difference in the first half. Sakho showed desire to beat Willian to the ball and composure to find Zaha, who finished expertly.
Victor Moses went off early in the second half as a hamstring injury appeared to impair another Chelsea player after N'Golo Kante and Morata. Fabregas hit the crossbar with a 25-yard strike before Pedro was sent on for Batshuayi, who showed frustration at being withdrawn after a rare start. Julian Speroni twice saved from Pedro and once from Alonso.
Charly Musonda, on for Willian, had a glorious chance, but, after controlling Fabregas' lofted pass on his chest, fired over. Palace had opportunities for a third as they finished on the attack.
Zaha tried to seize upon a mix-up between Bakayoko and Luiz, Townsend had an effort saved by Courtois, who was relieved to see the follow up sent wide by Van Aanholt