It was a weekend when Pep Guardiola's party was crashed by Jose Mourinho, Tottenham and Liverpool took over at the top of the table and Chelsea goalkeeper Edouard Mendy continued to demonstrate that – whoever agreed to pay £72m for Kepa Arrizabalaga should perhaps reconsider the day job – with his seventh clean sheet in 10 games. Those were some of the more obvious takeaways so here we cast an eye over some of the other issues you might have missed.

Robertson on the rampage

Liverpool's treatment room at their new training centre in Kirkby has had more drama than an episode of Holby City in recent weeks. Virgil van Dijk has been a regular visitor during his rehab from an anterior cruciate ligament, Trent Alexander-Arnold sustained a calf injury against Manchester City, Joe Gomez has had surgery to repair a tendon in his knee, while Jordan Henderson, Thiago Alcantara and Fabinho have all been nursing one injury or another. Meanwhile, Mo Salah tested positive for Covid-19 last week. So what happened yesterday against Leicester City? Everyone else stepped up as Liverpool won 3-0 against a team that came thinking they could give the depleted champions a bloody nose. No-one did more for Liverpool's cause than Andy Robertson who was a constant menace on Leicester's left, produced an arcing cross for Diogo Jota's goal to make it 2-0 and had 94 touches, the second most of any player on the pitch. After an international break when, despite helping his country to qualify for the European Championships, the Scotland captain looked out of sorts, here he played the role of a game-changer as he stalked the left flank causing the visitors all sorts of problems.

Nothing gets in the way of a Manchester United penalty

Another week, another Bruno Fernandes step, step, shuffle and goal. It's now 44 penalties in 127 games for the Red Devils. Move over death and taxes, there is another immutable, universal truth and that is that Manchester United will be awarded a spot kick if the circumstances allow it. At Old Trafford on Saturday not even a foul on the West Brom midfielder Sam Gallagher by Fred was enough to alert referee David Coote to the possibility that he might have intervened before Juan Mata's cross flicked off Darnell Furlong's arm. Sam Johnstone duly saved Fernandes' first effort but the hawk-eyed Coote noticed that he had stepped forward off his line before flinging himself to his left. It was a good spot by Coote, it was just a pity he hadn't noticed the equally obvious infringement by United's Brazilian midfielder mere seconds earlier.

Spurs' shape

It's winter, that time of year when starlings perform the act of murmuration, twisting and turning above a roosting site in polymorphous shapes before plunging into their nests. Perhaps Jose Mourinho spent the international break watching reruns of the BBC nature programme Winterwatch. Against Manchester City, there were times when every single Tottenham player was contained within camera shot as they formed a swirling mass that almost seemed connected by rope. It was instructive to watch because it was the first time Tottenham looked and felt as if they were finally 'a Mourinho team' as they strangled the space that City love to operate in. It is now a year since the Portuguese was appointed by Spurs and whether the work he has carried out so far is enough to turn them into title contenders will be given a stiff examination against third-placed Chelsea at Stamford Bridge next weekend. After that it's Arsenal, Liverpool and Leicester in quick succession.

Does anyone understand the rules any more?

Dean Smith admitted he was baffled when a last-minute penalty for Aston Villa against Brighton was overturned thus robbing his side of the opportunity to earn a point at Villa Park. Kevin de Bruyne spoke eloquently as he voiced his confusion over why Gabriel Jesus's was penalised for handball when setting up Aymeric Laporte for an equaliser against Spurs that was ultimately ruled out when Mike Dean consulted the pitch-side monitor. The Belgian pointed out that over the past couple of years the rules had changed so much that he no longer understood what was what. Giving referees a microphone and allowing conversations between the match referee and his video assistant would bring greater clarity. Furthermore, it might allow those in the dark to develop a greater understanding of why officials appear to arrive at seemingly arbitrary decisions from one week to the next without any sense of consistency.

Graham Potter gets a win at last

Anyone who has kept a close eye on Brighton & Hove Albion's results recently might have been led to believe that Graham Potter's side was struggling. Their last win came in the second game of the season against Newcastle United, an impressive 3-0 humbling which suggested the Seagulls might not spend the entire season hovering above the relegation zone. But, prior to the win at Aston Villa, three defeats and three draws had followed. It was inexplicable to anyone who had watched their performances because Potter and his assistant, the former Hamilton Academical manager Billy Reid, have Brighton playing an expansive, exciting brand of football with the marauding right-back Tariq Lamptey showing up as well as anyone in the Premier League – not just among full-backs but across the entire division. Brighton were robbed against Manchester United, deserved more than a narrow defeat at Tottenham and made Chelsea sweat on opening day. Saturday's win has been in the making for some time.