1 United's Anderson has reinvented himself

When Manchester United signed Anderson in 2007 the fee was never officially disclosed but widely put at £18m. It largely passed under the radar that Porto's accounts later revealed they had received €30m (£25.3m at today's exchange rates) for the Brazilian, making him the fifth most expensive player Sir Alex Ferguson has ever bought (behind Dimitar Berbatov, Rio Ferdinand, Juan Sebastián Verón and Wayne Rooney). It is a lot of money for someone who has scored only two goals in 110 appearances for the club but Anderson is, at least, now playing with the drive and purpose that should be expected. He was full of energy here, one of the outstanding performers of the night.

2 Arsène Wenger will live to regret not having a better goalkeeper

Perhaps there will come a time when Wojciech Szczesny's presence in goal will not fill Arsenal's supporters with a sense of foreboding. The Pole, to give him his due, is entitled to feel he could do little about Park Ji-sung's goal and, overall, he handled his first league start without showing too many nerves. It is a strange set of circumstances, however, that Wenger is trying to win the title without a goalkeeper on his books who inspires confidence. The shoot‑on‑sight policy operated by United's front players in the opening stages, in particular Nani, showed they were encouraged to find a relative novice (albeit one with three Poland caps) between the posts.

3 Arsenal need to keep Cesc Fábregas fit

Of all the Spaniard's qualities, he also plays with a big-game mentality. Arsenal were over-run at times in the midfield, particularly in the first half, and though Jack Wilshere is a vibrant and gifted footballer there will be a reassuring feel to the side for Wenger when Fábregas is able to resume his place in the starting line-up

4 Sir Alex Ferguson's words were wasted

United's manager made his point in his programme notes. "Before we get under way," he wrote, "could I make a special appeal to that small section of our fans who seem to get perverse pleasure from taunting Arsène Wenger with crude chants? He deserves better, much better." He had said the same on television and radio and the club followed it up in a text message to their season-ticket holders in the morning but on the first occasion Wenger left the dug‑out, after 69 minutes, the same abuse began, as loud as ever. "We're Man United, we'll do what we want," they sang.

5 Nani: potential footballer of the year

He will always jar with the way he looks for free-kicks and exaggerates injuries but the Portuguese has been the club's outstanding footballer so far this season and he made it a difficult evening for Gaël Clichy, usually an accomplished opponent. Samir Nasri, Arsenal's best player this season, took longer to get into the game. The Frenchman was involved in many of Arsenal's more penetrative moments but Nani had the greater impact, his cross setting up Park's goal and his menace leading to Clichy's handball for the penalty.