LONDON — Manchester United's troubled start to the season took another unexpected twist as it lost limply 3-2 at Brighton & Hove Albion Sunday with manager Jose Mourinho admitting they were punished for making too many mistakes.

Woeful defending led to two Brighton goals in two first-half minutes as 34-year-old Glenn Murray and Shane Duffy outsmarted United's 117 million pound ($149.21 million) back four to demonstrate why manager Jose Mourinho had sought to upgrade it.

Eric Bailly was particularly exposed and, having conceded a needless corner that led to Duffy's first Premier League goal, he blundered in to foul Pascal Gross, who put away the penalty via David de Gea's leg on the stroke of halftime.

Although Romelu Lukaku had earlier reduced the deficit with a trademark header, United looked ill-equipped to mount a comeback and was often second best to the ball.

Paul Pogba's injury-time penalty, after Marouane Fellaini was brought down, made the scoreline closer than the match itself with Mourinho admitting that his side deserved to lose.

"We made big mistakes and were punished," said Mourinho, although he refused to criticize individuals.

Brighton's Murray said their 3-1 home win over United last season gave them confidence that could spring another surprise.

Mourinho had started with Anthony Martial but the winger, who is reported to be unsettled at the club, made little impact even when Jesse Lingard and Marcus Rashford were brought on at halftime in an attempt to give United more of a threat up front.

Sergio Aguero netted his 13th hat trick for Manchester City as the champion made light of the absence of the injured Kevin De Bruyne to thrash Huddersfield Town 6-1 and move joint top of the Premier League.

The prolific Argentine scored on 25, 35 and 75 minutes, also hitting the post in a devastating display to which the visitors, who last season were the only side to stop City scoring in the league at home, had no answer.

Gabriel Jesus also netted, along with David Silva on his 250th league appearance for City, with the rout completed by a Terence Kongolo own goal late on after excellent work from substitute Leroy Sane.

"I am happy," said man-of-the-match Aguero, who was about to be replaced when he scored his third.

"I was a little bit tired. I try two or three times to get the third goal."

For once, Pep Guardiola chose to pair Aguero with Jesus up front and such were the array of City attacking options that Huddersfield was simply pulled apart.

Watford made it two wins out of two and ended its run of poor away form in impressive fashion as early second half strikes from captain Troy Deeney and Will Hughes gave them a 3-1 win at Burnley.

Watford, which has won its opening two games of the season for the first time in the Premier League era, had been winless in its last 12 away games and had not even scored on the road since January.

It took the visitors just three minutes to end that streak as former Burnley forward Andre Gray opened the scoring with a superbly taken volley from a fine Deeney cross from the right flank.

Three minutes later, though, Burnley got back on level terms when James Tarkowski rose well at the back post to head in a Johann Berg Gudmundsson corner.

Burnley, which has now gone seven league games without a win, was swept aside by two goals in the opening six minutes of the second half.

The influential Deeney drove home in the 48th minute after being found in the box by a clever pass from Abdoulaye Doucoure then a terrible giveaway by Burnley defender Matt Lowton to Will Hughes resulted in the Watford midfielder firing past Joe Hart with a brilliant left-foot strike. — Reuters