10 big questions from this weekend's Premier League action

theScore examines the most important Premier League developments by answering 10 key questions that arose from this weekend's slate of action.

Why can't Arsenal kill off matches?

Arsenal continue to throw points away.

The Gunners squandered two more potentially invaluable points Saturday against Crystal Palace, conceding a goal to the suddenly serviceable Jordan Ayew in a 1-1 draw at Selhurst Park. The fortuitous strike, which bumbled over the line with the help of a huge deflection, canceled out Pierre-Emerick Aubameyang's first-half tally, which has become a common theme this season for the north London club.

Aubameyang's red card in the second stanza - for a truly atrocious tackle - didn't help matters, obviously, but there are some deep-rooted issues at Arsenal that go beyond simply having bad defenders. There have been signs of life since Mikel Arteta took over, but there's clearly plenty of work to be done, which will almost certainly include multiple transfer windows worth of player recruitment.

Martial taking it to the next level?

Marcus Rashford has become a bona fide star this season, rising above the drivel that is Manchester United's inadequate squad and establishing himself as a legitimate, consistent scoring option; the 22-year-old has 19 goals in his last 23 matches for club and country. He's been one of the lone bright spots during an otherwise strange, uninspiring season at Old Trafford.

But he's not the only one who appears to making the leap.

Anthony Martial is in the midst of a career year, seemingly taking the next step in his development that's been expected since United spent a then-record fee to sign him as a teenager from Monaco in 2015. In 22 matches across all competitions this season, he's registered 11 tallies and three assists. It took him 38 appearances last season to be involved in the same number of goals (14).

His United career has been hindered by myriad disruptions - injuries, disarray at the club, and Jose Mourinho's tenure among them - but he seems to be putting it together now.

Bobby Firmino, Liverpool's MVP?

Virgil van Dijk gets much of the attention. Mohamed Salah has scored many of the goals. Sadio Mane is (finally) getting the love he deserves for being consistently excellent. The full-backs are the most celebrated in the game, and the midfield garners accolades for gluing everything together.

All for good reason.

There's plenty of praise to go around at Liverpool, but be sure to spare some for Roberto Firmino, who is arguably the most valuable member of Jurgen Klopp's unstoppable juggernaut.

The Brazilian striker will never put up the same raw scoring numbers as some of the world's most celebrated No. 9s, but his all-around game is something that will eventually be recognized as the blueprint for the modern forward.

He's quite good at actually finding the net, too, as he reminded everyone with his slick winner against Tottenham on Saturday.

When will Liverpool lose?

Maybe never?

The rampant Reds have cleared the midway mark of the Premier League season without defeat, and while it hasn't always been dominant, they've found the sweet spot of both playing well - spectacularly, at times - and getting the necessary fortune that every good side needs when things aren't quite clicking on any given day.

They're already undefeated in 38 league matches dating back to last season. It's beyond time that we start seriously considering the possibility that Liverpool may become the latest team to join the exclusive "Invincibles" club.

Midfield solution for Mourinho?

Tottenham spent the first 45 minutes of Saturday's loss to Liverpool bunkered in their own end, looking totally incapable of keeping possession and stringing more than a single pass together. At multiple points in the half, a Spurs player, under little or no pressure, simply hoofed the ball forward into the abyss and prepared for another attacking wave from the visitors.

They looked, in a word, intimidated.

There was a change of tack after the interval, though, to the point where Tottenham were probably right to feel aggrieved that they didn't get a point out of the contest.

That was largely down to the 69th-minute introduction of Giovani Lo Celso, who replaced Christian Eriksen. Where the Dane looked sluggish and disinterested, the Argentine was buzzing; his energy, pressing, and incisiveness caused real problems for Liverpool's backline.

The only blight on his record was an almost inconceivable close-range miss that sent Mourinho to his knees. Regardless, Lo Celso showed in just 20 odd minutes that he can be the anchor around which Tottenham's midfield is built.

No Kane, no problem for England?

Harry Kane is slated to be sidelined until at least April after undergoing surgery to repair a torn hamstring. It's the latest in an ever-growing list of serious injuries sustained by the once explosive Tottenham striker.

Wild as it may seem to suggest - he's England's captain, after all - a glut of talented scoring options means Gareth Southgate might need to seriously start considering building his attack around someone else moving forward.

Rashford, as already outlined, is in the midst of a career season. Tammy Abraham is proving his Championship scoring prowess was no fluke, and even Danny Ings is putting up better numbers than Kane this year. Heck, maybe Jamie Vardy could be lured out of international retirement.

The Three Lions, with or without Kane, are well stocked heading into Euro 2020.

Are Leicester in trouble without Ndidi?

It's no coincidence that, in their first league match without indomitable ball-winning midfielder Wilfred Ndidi, Leicester City conceded 16 shots - seven from inside the penalty area - en route to a 2-1 home defeat to Southampton.

The 23-year-old Nigerian, who's N'Golo Kante-like in his ability to shut down an opposition attack, is out indefinitely after undergoing knee surgery. To say he'll be sorely missed would be a massive understatement.

Among players with over 1,000 minutes logged in the Premier League this season, nobody has recorded more tackles per 90 minutes that Ndidi (4.4). His mobility and uncanny ability to recognize danger have been vital in helping the Foxes establish themselves as a serious top-four threat.

There's plenty of hope and excitement surrounding Hamza Choudhury at the King Power Stadium, but he's not ready to fill Ndidi's sizeable boots just yet.

Southampton teaching everyone a lesson?

Southampton could have cut bait with manager Ralph Hasenhuttl after their humiliating 9-0 defeat to Leicester in late October. God knows many other clubs would have been quick to pull the trigger after such a traumatic result.

Instead, the Saints exercised some patience - a trait that seems increasingly rare in sports these days - and are now reaping the benefits. A fourth win in five league games has Hasenhuttl and Co. seven points clear of the relegation zone, with the red-hot Ings leading the way.

Don't look now, but a spot in the top half is well within reach.

Rock bottom for Bournemouth?

Bournemouth dropped into the relegation zone after a harrowing 3-0 home loss against Watford on Sunday, as the latter pulled themselves out of the bottom three for the first time this season. Nigel Pearson, incredibly, has been a godsend for the Hornets.

Eddie Howe, on the other hand, is surely approaching the end of his leash at the Vitality Stadium. The Cherries' slide, and Howe's potential dismissal, were pertinent topics in this space on New Year's Day, too, and the questions over his future will only intensify amid a brutal run of just four points from the club's last 11 league matches.

The time for sentimentality has surely passed for Bournemouth who, unlike the aforementioned Southampton, don't have the underlying performances to suggest that patience is warranted.

Best foreign player in league history?

There are plenty of contenders for this (fictional) crown, but Sergio Aguero is surely in contention.

The Manchester City striker surpassed Arsenal icon Thierry Henry as the highest-scoring foreign player in Premier League history on Sunday, pushing his tally to 177 goals with a hat-trick in the Citizens' destruction of Aston Villa. His third marker in the 6-1 win also gave him more hat-tricks (12) than anyone else to ever play in England's top flight, foreign or otherwise.

He'd scored at least 20 goals in six of his eight Premier League seasons coming into the current campaign, and with 13 tallies so far this time around, the devastatingly consistent Argentine is well on his way to reaching that benchmark once again.

Others may have a better claim as the league's greatest non-British player, but as a pure scorer, the 31-year-old is unrivaled.