Pre-season optimism can be a dangerous thing, as Manchester United fans have found out the hard way.

On Saturday Michael Carrick's side suffered a shock 2-0 defeat at newly promoted Hull City, who were by far and away the better side.

Hull, back in the Premier League after nine years away, had never previously beaten United in the top flight.

It is the first time United have lost to a newly promoted side on the opening game of the season.

The consolation for United is that it is not the first, nor will it be the last, opening-day upset.

BBC Sport looks at some of the most shocking opening-game defeats.

2021-22: Brentford 2-0 Arsenal

In 2021, Arsenal were not the Premier League champions they are now, but an opening defeat by Premier League newcomers Brentford was still a major upset.

The Bees were expected to go straight back down to the Championship, but they overpowered Arsenal at a vociferous Gtech Community Stadium.

What a way to mark your first Premier League match, and the first Premier League match without capacity restrictions since the Covid-19 pandemic.

2017-18: Chelsea 2-3 Burnley

Chelsea fans could not have imagined a worse start to their Premier League title defence.

Gary Cahill's red card 14 minutes in gave Burnley an early man advantage, and Sean Dyche's side led 3-0 by half-time.

Chelsea fought back in the second half, but Sam Vokes has already done the damage at Stamford Bridge.

Cesc Fabregas' late dismissal meant Antonio Conte's side ended the day with nine players.

2013-14: Arsenal 1-3 Aston Villa

Remember Antonio Luna?

The Spanish full-back only lasted one season in the Premier League, but he scored Aston Villa's third to wrap up a superb 3-1 win away at Arsenal.

After scoring 19 goals the previous campaign, Belgian striker Christian Benteke scored twice before Arsenal's day got even worse when defender Laurent Koscielny was sent off.

This was a bit of a bad-tempered affair - with nine yellow cards and one red. No opening-day game has ever seen so many cards.

2012-13: Queens Park Rangers 0-5 Swansea

Surely nobody has enjoyed a better Premier League debut than Michu?

Swansea's Spanish magician scored twice and set up another as his side thrashed big-spending Queens Park Rangers in West London.

It was a shocking defeat that set the tone of the season for QPR, who despite signing practically a whole new starting XI, ended the season rock bottom of the table.

2012-13: West Brom 3-0 Liverpool

On the same opening weekend, Brendan Rodgers' tenure as Liverpool boss began with a chastening 3-0 defeat away to West Brom.

Liverpool looked shambolic, summed up by defenders Daniel Agger and Martin Skrtel getting sent off and conceding a penalty respectively.

Romelu Lukaku scored the first of 17 Albion goals during his season on loan from Chelsea.