It would not be a Premier League opening week without football-starved fans and pundits leaping to some kneejerk conclusions.

Sunderland, tipped by many to make a swift return to the Championship, caused the biggest upset of the weekend with a thumping 3-0 win over West Ham, marking their first Premier League success in the month of August since 2010. Suddenly Sunderland are being talked up as safe, West Ham as doomed, and Graham Potter already on borrowed time.

Brentford, Burnley and Everton joined West Ham in being dragged into the relegation fight conversation, with their respective 3-1, 3-0, and 1-0 defeats sparking talk that all could now be in for a tense survival battle.

It was not just the bottom of the table making headlines; Pep Guardiola’s six-time champions, Manchester City, ranked third favourites behind Arsenal and Liverpool for the title this season, swept aside Wolves 4-0 thanks to two goals from Erling Haaland. The result made them the Premier League’s most in-form side over the last 20 games with 43 points, and reignited talk that City look back to their pre-Rodri injury best, with Haaland firmly on course for another Golden Boot.

Liverpool’s 4-2 win over Bournemouth has dampened talk of another comfortable title charge, with defensive frailties drawing concern and the former defender Jamie Carragher warning: “If Liverpool continue like that, I don’t think they will win the league.”

Elsewhere, Chelsea were described as rudderless in their 0-0 draw with Crystal Palace, raising concerns that they need another gear, a far cry from their pre-season hype as top-spot challengers.

Unfortunately for the likes of Sunderland and Manchester City, and perhaps fortunately for those sides already written off, history shows that the first day of the season is not a reliable indicator of how a team will fare over the campaign.

A glance back at previous seasons provides plenty of evidence. Sunderland fans, in fact, should know better than most that an opening-day win is no guarantee of a smooth season. In 2007-08, the Black Cats began with a last-minute Michael Chopra winner against Spurs, only to finish just three points above the relegation zone. A more striking cautionary tale came in 2010-11, when the newly promoted Blackpool thrashed Wigan 4-0 on the opening weekend, sparking survival hopes. They went on to win just nine more league games all season and dropped straight back into the Championship. One good afternoon in August can be quickly forgotten once the grind of the full season sets in.

On the same weekend that the Seasiders were revelling in their first top-flight win in over 39 years, fellow newly promoted side, West Brom, were on the receiving end of a 6-0 battering from Chelsea. While most assumed they were nailed on for the drop out of the two sides, it was Roberto Di Matteo/Roy Hodgson’s side that stayed up, finishing 11th in the league. Burnley fans will no doubt take solace in hearing this.