Arsenal completed a dreadful week by losing 2-1 at Brighton in the Premier League on Sunday to slip 13 points off the Champions League qualification positions and pile more pressure on manager Arsene Wenger.

After back-to-back 3-0 losses to Manchester City across two competitions, Arsenal stumbled again following two errors by goalkeeper Petr Cech on the south coast.

Cech was beaten to a high ball following a corner to the back post, and Lewis Dunk slotted the loose ball home from the edge of the six-yard box in the seventh minute.

Brighton's Lewis Dunk, right, celebrates scoring his side's first goal of the game during the English Premier League soccer match between Brighton and Arsenal at the AMEX Stadium, in Brighton, England, Sunday March 4, 2018. (Gareth Fuller/PA via AP)

Glenn Murray made it 2-0 in the 26th when his header from Pascal Gross' pinpoint cross squirmed under the diving Cech.

Pierre-Emerick Aubameyang reduced the deficit for Arsenal by turning in Granit Xhaka's drive across the face of goal in the 43rd, but the visitors couldn't turn sustained pressure into an equalizer in the second half.

It was Arsenal's fourth straight loss in all competitions, and eighth in 14 matches in 2018.

Brighton's Glenn Murray scores his side's second goal of the game, during the English Premier League soccer match between Brighton and Arsenal at the AMEX Stadium, in Brighton, England, Sunday March 4, 2018. (Gareth Fuller/PA via AP)

Arsenal is in sixth place and destined for another year out of the Champions League, unless it can win the Europa League to earn a direct passage to Europe's top competition.

Arsenal lost to City in the League Cup final last Sunday and then in the Premier League on Thursday, placing Wenger under renewed scrutiny in his 22nd season in charge.

Manchester City's Bernardo Silva, center, challenges for the ball with Chelsea's Marcos Alonso during the English Premier League soccer match between Manchester City and Chelsea at the Etihad Stadium in Manchester, England, Sunday, March 4, 2018. (AP Photo/Rui Vieira)

Man City beats Chelsea 1-0, leads EPL by 18 points

Bernardo Silva scored inside 33 seconds of the second half to earn Manchester City a 1-0 win over Chelsea on Sunday that moved the leaders to within 12 points of clinching the Premier League title.

With its 14th straight league win at home, City opened up an 18-point lead with nine games remaining as Pep Guardiola's side continues to show no mercy on its way to a second trophy of the season after the League Cup.

Chelsea, missing key midfielder N'Golo Kante, played ultra-defensively in the first half — it didn't even have a shot — only to concede immediately after the restart when David Silva crossed for Bernardo Silva to force in a finish at the far post.

Manchester City's Bernardo Silva celebrates with his teammates after scoring his side's opening goal during the English Premier League soccer match between Manchester City and Chelsea at the Etihad Stadium in Manchester, England, Sunday, March 4, 2018. (AP Photo/Rui Vieira)

Chelsea stayed in fifth place but is now five points adrift of the fourth and final Champions League qualification position — currently occupied by Tottenham — and 25 behind City.

It was a second straight loss in Manchester for Chelsea, having been defeated 2-1 by Man United last weekend.

The possibility remains open that City could win the league title at home to United on April 7.