One trait of a title-winning team is the ability to come from behind to win games.
Manchester United's recovery from two-goals down at Blackpool last week, to win 3-2, is a classic example of this - they were trailing 2-0 with only 18 minutes left and defeat would have cut their lead at the top of the table to just two points.
If they go on to win the title, it could be one of those games where they look back at the end of the season and say 'that was a turning point'.
At one point, both London clubs were losing - to Everton and Sunderland respectively - and United were set for an eight-point lead at the top of the Premier League. Again, potential turning points in the season.
Tellingly for Chelsea though, it was only the second time this season that they have won a game after conceding the first goal - the other being a 2-1 win at Blackburn Rovers.
Of the nine times they have gone behind initially, five have ended in defeat. That is something they will need to address if they are to catch United and Arsenal - they are still 10 points behind Sir Alex Ferguson's team.
Arsenal meanwhile, preserved a six-match winning run in all competitions - their best streak of the season. They have managed to salvage at least a point from five of the eight games in which they conceded first. The first half of United's season was notable for conceding late goals, but they remain unbeaten and the fact that they have only let in the first goal in four games is an obvious factor in that run.
It proves the importance of scoring first in a league where more teams look capable of winning the title than ever before.
Of the final two teams in the title equation - Manchester City in third and Tottenham Hotspur in fifth (both in action last night) the contrast is vast. City have only managed to win one of the six games in which they conceded first. Spurs have let in the first goal 12 times, yet have turned five of those games into victories
It is evidence of Tottenham's you-score-three-we'll-score-four mentality, and while City have won more games they appear fallible if they don't have the lead.