1 United refuse to give up their title

Witnessing stoppage time at the Etihad Stadium must have been crushingly deflating for Manchester United, a sense that fate is with Manchester City's championship bid inescapable. Even Sir Alex Ferguson's pre-match assessment that "what we've got to do is make sure we keep on City's coat-tails" felt resigned. Yet, while there are clear weaknesses in their makeup, psychologically this United team retain strength. This game was a test of their powers of reaction, an examination even sterner once Arsenal had revived after the interval and equalised. Yet Danny Welbeck's winner sent out a message: this is not City's title just yet. The pursuit has been maintained.

2 Doubts remain over United's backline

The champions would argue this represented one of the more daunting trips of the campaign, though the shortcomings of their rejigged and reshaped backline are all too evident these days. Arsenal may have pressured them only in fits and starts but United still creaked, particularly at the beginning of the second half as panic threatened to set in. With Nemanja Vidic a long-term absentee and Rio Ferdinand missing here, there was a fragility to United's defence. Neither Jonny Evans nor Chris Smalling tracked Robin van Persie as he collected Alex Oxlade-Chamberlain's reverse pass to equalise, and other opportunities had been desperately denied up to then. Winning the Premier League title with such an inexperienced rearguard would constitute a considerable achievement for Ferguson.

3 United miss utility player of choice

The cameras focused on Fabio Capello as Phil Jones was carried round the touchline on a stretcher, though the watching England manager's concern will have been felt more keenly than Ferguson. The damage sustained to the utility player's left ankle as he stumbled in retreat from Theo Walcott will be determined once the swelling recedes, but his discomfort was clear and ominous. While England wonder about Euro 2012, United will ponder whether right-back is fast becoming a position of real concern. Smalling has featured there but was required centrally here. Rafael da Silva, Jones's replacement, is still raw, had been booked by the break and was subbed himself before the end. If there is a position where an addition must be made this January, it is here.

4 Valencia's return offers reassurance

The Ecuadorean winger maintained recent high standards, unsettling Thomas Vermaelen – a stopgap left‑back – with slippery skill and a crunching header for United's first-half reward. The 26-year-old offers balance and bite, his rhythm thankfully now restored. Perhaps Valencia needed longer to recover fully from the fractured ankle suffered at Rangers in September 2010. He missed much of pre-season last summer after succumbing to injury at the Copa América which certainly set him back but this was like old times with his tormenting of Andrey Arshavin for his side's second proving as much.

5 Arsenal have been cast to periphery

For much of the second period the momentum was with Arsenal, the home support driving them on in pursuit of their equaliser, only for the mood to turn poisonous. Oxlade-Chamberlain's substitution for Arshavin had the locals in open revolt, the abuse raining down on Arsène Wenger when the Russian was half-hearted in tracking Valencia for United's winner. The title has long gone but a third successive league defeat leaves fourth place five points away, and the third-placed Tottenham Hotspur still 10 clear. Results have reverted to the misery of autumn. The disaster Wenger had feared – a failure to reach the Champions League – may well now become a reality.