5 things we learned in the Premier League this weekend: Anthony Martial is good at 1st impressions

With another weekend of Premier League action in the books, we take a look back at five things we learned from the latest slate of matches.

Anthony Martial might be worth £36 million

On Saturday, Anthony Martial became the first Manchester United player to make his debut versus Liverpool at Old Trafford since John Thompson did so in 1936.

And just like Thompson, the 19-year-old wasted no time in scoring his first goal for the Red Devils.

Martial scored only 21 minutes after he took the pitch during United's 3-1 victory against the Merseyside club, instantly shutting up those who argued that £36 million was too much to spend on someone barely old enough to drink in the United Kingdom.

Only time will tell whether Martial can indeed justify his hefty price tag, but he scored with his first shot in the Premier League and with just his sixth touch for United, producing a debut that was as impressive as they come.

Something is very wrong at Chelsea

If, prior to the season, someone had suggested that Chelsea would lose three of its first five matches, the comment would have been regarded as wishful thinking rather than a calculated prediction.

Yet, after a 3-1 defeat at Everton in which Steven Naismith came off the bench to score a perfect hat-trick, the reigning champion finds itself hovering above the relegation zone, seemingly incapable of winning any game and possessing a backline that looks like a shadow of what it was only months ago.

Chelsea's defensive issues can be summed up by its average of 2.4 goals conceded and 7.6 shots on target allowed per game, numbers that provide a stark contrast to the 0.8 goals conceded and 3.2 shots on target allowed per game that the club averaged en route to its fourth Premier League title.

Perhaps Cesc Fabregas' red card in May is to blame.

Riyad Mahrez is the best player in the league

The word "effortless" comes to mind when attempting to summarize what Riyad Mahrez is doing at Leicester City this season.

Leicester is the talk of the Premier League, sitting second in the table after a phenomenal 3-2 win versus Aston Villa in which Mahrez inspired a comeback that saw the Foxes find three goals in the last 20 minutes of the second half.

Related: Anarchy in the Premier League - Riyad Mahrez is rewriting the script

Mahrez is spearheading a revolution at King Power Stadium, fuelling a success of which the club has been starved. The two assists he tallied versus Villa served as evidence of his undeniable talent, but it was the way he dribbled through opposing players in Lionel Messi-esque style that have triggered comparisons to the planet's top footballer.

Crystal Palace knows how to contain Manchester City

Crystal Palace was only minutes away from becoming the first club to deny Manchester City of a victory this season. Then, an 18-year-old striker named Kelechi Iheanacho, or "Whatever his name is, that fella, No. 72" as ex-footballer and television presenter Chris Kamara put it, entered the fixture and scored a 90th-minute winner to maintain City's 100-percent record.

It was a cruel result for Palace, who had kept City at bay throughout most of the match and deserved at least a point against the Citizens, something no other side can truly say this season.

Any side wondering how to shut down City should ask Palace.

Kelechi Iheanacho makes the most of his opportunities

Speaking of Iheanacho ...

With his late winner at Selhurst Park, the teenager instantly transformed himself from an unknown quantity whose name could barely be pronounced to a local hero.

Iheanacho had played a total of one minute for City before entering the game and scoring the club's winning goal. At a club where minutes are hard to come by, even for the most established of footballers - just ask Nicolas Otamendi - the youngster likely ensured that his name will be included on a few team sheets throughout the rest of the season.