Eight seasons ago Sam Allardyce's Bolton Wanderers finished the old year in the top four of the Premier League, then won only four more games and finished seventh. Contests against Chelsea and Arsenal in the next week will give an early indication of whether West Ham United, equally unexpected high-flyers, can stay at rarefied altitude any more convincingly.
The 2-0 victory over Leicester City pushed them closer to the top three and will send the players to Stamford Bridge more confident about their attacking threat than last January, when Chelsea had 39 attempts in a goalless draw and their manager, Jose Mourinho, accused the visitors of playing "19th-century football".
Allardyce could afford to smile at the recollection on Saturday, pointing out how significant that game had been for a team lying 18th at the time, who went on to win their next four matches: "The turning point why West Ham United stayed in the division eventually was the draw at Chelsea," he said. "That's how important it was. It gave the lads a huge confidence boost and huge belief that they could hold a team like Chelsea off and we went from there on to make ourselves safe in the league. We'll see what century we're in when we finish there."
Andy Carroll, as he often seems to be, was part of the backstory on that occasion, playing his first full game of the season and clearly less than fully fit.
Against Leicester, he was more like the Carroll of old, winning high balls, knocking defenders over when he couldn't and - more surprisingly - scoring his third goal in three games with a finish that Lionel Messi would not have sniffed at. It was his 12th for West Ham and reckoned to be only the second with his feet; he should try it more often.
Although both goals stemmed from a long punt out of defence, by Carl Jenkinson and James Tomkins, there is greater subtlety to the team's play.
Leicester, meanwhile, know they ought to strengthen the squad next month after collecting have collected two points from the last 36 available. Nigel Pearson was a coach at West Bromwich Albion when they became the first Premier League team bottom of the table at Christmas to avoid relegation, 10 years ago.
He would doubtless prefer to forget that they did it after changing the manager but insisted: "There are similarities [to Leicester]. Ultimately, you do need people who are capable of dealing with adversity and have the strength of character and inner belief to come through difficult times."