Very few thought either Arsenal or Manchester United would be in the Premier League title race at the halfway point of the season, but the fallen giants meet at the Emirates on Sunday with the trophy very much in their sights.
United are without a top-flight title in a decade and registered their worst-ever Premier League points total last term. Arsenal's last league triumph was in 2003, and they have not finished higher than fifth in the previous six seasons.
This time around, however, both have turned things around - especially the Gunners, who hold a surprising five-point lead over nearest challengers, champions Manchester City, at the top of the standings going into the weekend's matches.
Earlier in the Premier League era, clashes between Arsenal and United were often blockbuster occasions between title chasers. Tempers boiled over on many occasions, including the infamous 'pizzagate' tussle in 2004.
Sunday's encounter at the Emirates is the third time Arsenal are hosting United in a Premier League match while top of the table, but the first since a 2-2 draw in Nov 2007.
United missed the chance to close the gap to Arsenal to six points on Wednesday after Michael Olise's last-gasp leveller earned Crystal Palace a 1-1 draw against Erik ten Hag's in-form side, the first time they had been denied victory in 10 games in all competitions.
The late equaliser was not the only setback United encountered on Wednesday. Instrumental midfielder Casemiro picking up his fifth caution of the season, meaning he will be suspended for the encounter.
Ten Hag is still confident United can complete a league double over the Gunners without the Brazil international, having beaten the London side at Old Trafford last September.
"Last time we beat Arsenal without Casemiro," the Dutchman said after the Palace draw.
"Casemiro is obviously a really important player for us and he is one of the reasons that we are in the position that we are now.
"We have a squad and we have to fill that gap and make a proper plan and the squad has to fill it. As a team, we already showed how to beat Arsenal."
BATTLE OF THE UNDERPERFORMERS
On Saturday, two teams with contrasting fortunes to Arsenal and United meet at Anfield as Liverpool, in ninth, host 10th-placed Chelsea with both desperate for a victory to resurrect their faltering campaigns.
Many expected Liverpool and City to compete for the title again this season, but the Reds have endured a miserable term thus far.
Their dismal performance in the weekend's 3-0 loss at Brighton & Hove Albion meant Liverpool lost back-to-back Premier League games for a second time this season.
They have suffered six defeats overall, three times as many as in the entirety of 2021-22.
Big things were expected of Chelsea after they spent big in the close season. But after replacing Thomas Tuchel as the Blues boss in September, Graham Potter has failed to inspire his new side.
The new signings have continued to arrive in January, but their form remains below par. Chelsea have won just two of their last 10 league games, though they did beat Crystal Palace 1-0 last time out.
Away from home, the Blues are winless in five league matches, their longest run since September-December 2015.
It had appeared City's chances of a fifth league title in six seasons were slipping away from them on Thursday night as goals from Dejan Kulusevski and Emerson Royal gave Tottenham Hotspur a 2-0 half-time lead at the Etihad Stadium.
However, the champions were a different team after the break, with three goals in 12 second-half minutes turning the match on its head. Riyad Mahrez added a late fourth to put the seal on a win that moved City to five points below Arsenal.
The match also saw Erling Haaland end his mini-goal drought to move on to 22 league strikes for the campaign - the most by a Manchester City player in a single league season under Pep Guardiola.
Guardiola's team host Wolves on Sunday and could be two points behind Arsenal before the Gunners kickoff against Manchester United later in the day.
Fourth-placed Newcastle United travel to Crystal Palace on Saturday while, down at the other end of the table, West Ham United host Everton, with both sides marooned in the bottom three and desperate for points.